Contract Manufacturing Prototyping

Prototyping is the early stage of contract manufacturing process, which is used to validate product feasibility and structure. If you want to get your products massive manufactured with a contract manufacturer, it’s necessary to prepare some prototypes with them. Otherwise it might bring your cost lost and project failure. Here below we will discuss prototyping in details:

What is a prototype, why build them?

Reasons for prototyping

Early and mid stage product development or contract manufacturing process requires prototyping – whatever the product, and nothing builds confidence like seeing how the product looks, experiencing how it functions and putting an excellent example in investor and customer hands early.

Whether it’s to test aesthetics, raise funds, evaluate function or make pre-sales before mass production, prototypes can give an edge and short cut manufacturing problems, tell your team they’re on the right track and even allow product certifications to start early.

Earlier identification of issues and challenges during development means it costs less to fix them. Prototyping allows earlier assessment of final Bill of Materials costs, allowing you to adjust price points without market disturbance.

Not testing your product sufficiently before shipping out is a key and commonplace reason for failure in startups – but you don’t need to break the bank to build confidence in your decisions.

Classifications of prototype

The Proof of Concept (PoC)

The proof of concept prototype is often the first solid and touchable representation of a development stage, allowing the start of assessment of real world feasibility.

For ‘mechanical’ products, the proof of concept needs to demonstrate functionality and can be quite far from the real thing in look, feel, materials etc. For primarily aesthetic products, more subtle methods are required to reproduce a real feel and look to evaluate the product – but still it can be quite far from the real thing.

For electronics based products, use developer kits and existing modular hardware to simulate the product – testing function on bare boards. All major hardware and processor platforms are supported by developer kits which expose the core functions to real world interface without any manufacturing burden, so it is possible to platform test with closer-to-real hardware, though this often requires more experienced engineering provision.

Whatever the product type, the purpose served by a POC is to prove the concept of the function of your product, so issues like aesthetics (unless that is a ‘function’), materials and finished product design are not a priority. For example, electronics can be enclosed in an off the shelf plastic or metal box with holes drilled in for buttons, or left exposed on naked circuit boards. For aspects such as strength, waterproofing, shock absorption, interference and others, more advanced prototyping can be required for particular aspects – but still the PoC can be minimised in other regards. 

Cosmetic Prototype

A cosmetic and initial mechanical functions prototype has limited user-functionality or strength, but possesses close to the true final appearance of the real product concept. First cosmetic prototypes are usually the output of the industrial design phase, where the outward look, materials, finishes and textures of the product are embodied. This allows early assessment of; manufacturability; cost blowout risks; functionality assessment; design practicality; etc.

Industrial design answers questions of aesthetics, CMF (Colour, Materials, Finishes) and the experience of the user in the handling of the product – though rarely its use, unless the product is essentially static and decorative, where aesthetic factors ARE the use.

Mockups carved from clay, foam etc play an important role in delineating the shape and ergonomics of products. Many early stage evaluations rely on having this type of prototyping completed to a high standard – allowing investor design evaluation for funding, user experience assessment and advertising, among other aspects, to proceed. This is particularly important for products that are developed as wearables or to be hand-held, as it allows the human interface aspect to be evaluated early.

Appearance prototypes are commonly used for stimulating market attention, the earliest market engagements and demos.

Later, carved approximations and purely modelling materials give way to parts made by precise and repeatable methods, from materials that increasingly simulate ‘real’ production. As these cosmetic prototypes evolve along with the design they will allow precise evaluation of assembly methods, fixings, manufacturing methods and user functions – particularly as stronger and more realistic materials are employed.

Functional Prototype

Full functioning prototypes are more demanding and require development work to have progressed to being close-to the ‘real’ product.

This can entail making precise and near full strength plastic and metal components and likely requires tight dimensional tolerances for a variety of aspects – moving mechanisms, functioning dust or water exclusion (IP rating), optical quality parts (light guides, display windows etc), user accessible connectors for data, charge etc and a host of hard-to-achieve aspects, fixing and mounting points etc.

The great majority of high value products contain electronics assemblies – and this has developed into a critical and invaluable aspect of the prototyping services sector.

Developer kit electronics enables quick evaluation and debugging, but this is not a solution that gets a product advancing fast towards mass production. With the functionality of the product proven, a custom designed PCB quickly becomes a necessity. This is the process whereby your work is transformed from a validated idea to a product. In particular you will need to make certain of the interface points between circuit boards and their components and the rest of the product – building accurate 3D files of the PCBa to add into your CAD process.

It is normal, at this stage, to hand the refined design schematics over to a specialist PCB engineering service provider, to get up to date and honed skills in track layout for thermal, RF and signal integrity issues. Competent general experience is sufficient for simple products, but complex signals, RF emissions and susceptibility, battery management, thermal issues and power consumption management are specialist areas in PCB engineering. With a finalised and tested schematic (simulated in any of a wide range of packages), a full set of PCB files (Gerbers) and an indented and supplier assigned costed BOM, you are ready to build your first custom electronics assembly (PCBa).

Nearly Real Product Prototype – 𝞪 prototype (where cosmetic  merges with function)

Generally referred to as ‘engineering prototypes’, this is the stage where function and cosmetic prototypes become one – and get as close to the final product as it’s possible (or desirable) to achieve.

This stage includes tight control of PCBa placement and the interfacing between mechanical and electronic assemblies. CAD files and specification notes for prototyping using techniques such as CNC machining and 3D printing will be circulated to appropriate suppliers but assembled in-house. Optimisation design changes that result from this generation must be integrated into the product, so at least two generations of engineering prototypes will be required for any but the simplest products.

Nearly Real Product Prototype – 𝜷, 𝙜 etc. prototypes

Later engineering prototypes are very similar to the first in appearance and functionality, but the overall design has completed increasingly rigorous DFM optimisation. Often these prototypes are made by processes that closely resemble the high volume manufacturing methods. Vacuum casting/silicone moulding is a process that approximates injection moulding, but allow multiple prototype parts to be made in essentially strong materials. CNC machined parts can closely parallel stamped/forged/cast metal components – and machined plastics can be truly representative of the final planned polymers.

This (likely final) generation of non-production prototype product can be used for real user evaluation, sales meetings, and very importantly FINAL certification processes such as FCC, UL, CE, RoHS, Bluetooth SIG without waiting for real production. They will likely undergo initial environmental testing for reliability and potentially HALT (Highly Accelerated Life Testing) to assess MTBF (Mean Time Between Failure) and later stage design risks.

Pre-Production Prototype – the Golden Sample

The pre-production prototype is the closest approximation to a mass-produced product achievable, before a production line is operating – the “Golden Sample”. Tools for the injection moulded parts are completed and tested and no major changes can be made – the design is ‘frozen’ and any required changes must balance the effect in delaying production and incurring significant re-work costs.

These prototypes will also be utilised for detailed test and evaluation, to ensure the design is right-enough before pre-production in the factory. These tests fall into three broad validation categories;

Engineering Testing. This confirms that the product meets functional, use/abuse and manufacturability requirements defined in the specifications

Design Testing. Increasingly ‘real production’ prototypes undergo a series of normal use and normal abuse stress tests. Environments requirements vary, but most products must endure some of; Dust exposure (IP_X); wetting and submersion in water (IPX_); drop testing; wet heat and temperature cycling; vibration; and more. Pass/fail criteria will assure that the design meets performance requirements – or inform changes that allow tests to be repeated on fresh samples.

User Testing; This confirms that the user experience is as expected and good enough for the product to succeed. A wide spectrum of evaluations may be required, for complex products; user comfort; keyflows and software stability; health and safety (users and others); price testing; storage evaluation; accessories and carry cases; expected and unexpected abuse by the user; and much more. These tests can critically improve details of the product function and presentation and alter the market positioning dramatically.

Services Required for Prototyping

Part prototyping digital technologies fall into two broad categories; additive and subtractive/extractive.

Pseudo production moulding processes such as silicone moulding (also known as vacuum casting) of polyurethane parts offer some advantages in material strength and are best where multiple prototypes are needed. The tooling costs will generally be recoverable over 2-3 uses, compared with 3D printing options.

Electronics prototyping methods are also critically important.

Additive Manufacturing/Prototyping

Additive processes build up parts from layers of powder, liquid or melted strand feedstock, using a variety of approaches to filling voids and supporting layering. They can exploit a very wide range of source materials and offer a wide range of work-area sizes, speeds, costs and precision levels. The technologies offered in this category are developing quickly – getting closer to real production material properties and improving resolutions at an accelerating pace. Generally referred to as 3D Printing or Rapid Prototyping, these are the more common types of process;

Fusion Deposition Modelling (FDM): This is among the lowest hardware cost for 3D printing and has been widely adopted in-house because of this and the fact that it is office friendly. This method can deliver prototypes with modest accuracy of detail, due to the resolution being set by the feedstock diameter – and narrower feedstocks resulting in huge build times, as the machines offer a single point of build that scans relatively slowly. FDM builds by delivering feedstock through a heated nozzle and depositing a melted and partially fused line of material. Fusing is incomplete because of the resolution, so parts are relatively weak, not water/air tight and of fairly low cosmetic standard. FDM is well suited to coarse and simple models where little strength is required – and they do not lend themselves to cosmetic finishing. Theoretical resolutions (detail size and later thickness) range from 1mm down to 0.2mm.

Stereolithography (SLA) or Tank Photopolymerisation; This is a relatively fast and moderate cost technique that uses a layer polymerisation/curing of photosensitive monomers which solidify when exposed to ultraviolet (UV) light. Resolutions can be the best in the sector – 16µm is available, most operate at 48µm

Digital Light Processing (DLP); Evolved from SLA, this system achieves polymerisation of resin layers using a conventional (non laser) light source. It requires the use of post-build cure stages to stabilise and finish parts – which can result in sag and distortion.

Continuous Liquid Interface Production (CLIP); Similar to SLA, but this system pulls/lifts the completed part from a fluid filled tank, where the cured layer is at the fluid interface.

Selective Laser Sintering (SLS); Suited to a wide range of plastic feedstocks, SLS builds prototypes from powdered beds of powder material, fusing dots by applying heat using a laser. Surface of the finished product is usually rough, material properties are close to the as-moulded in real production materials and porosity is very low. Resolution is defined by particle and laser size.

Selective Laser Melting (SLM) or Powder Bed Fusion; Analogous to SLS, this process uses metal powders and typically uses an electron beam to perform the fusion, though it can also be done using much higher laser power ratings than SLS. Resolutions are set by beam and powder size and surface finish tends to be moderate to good, but post machining is required for fit and bearing surfaces.

Binder Jetting; This technique produces parts that are not as strong as those created using other methods – but offers the advantage of colourisation by layer, allowing real coloured components to be built. The method also uses a powder bed (often of starch or plaster), but nozzles spray droplets of cyanoacrylate resin to bond the powder particles together to form the layers. Colour can be ink-jet printed in the same steps.

Laminated Object Manufacturing (LOM) or Sheet Lamination; A lower cost process that is office friendly – i.e. does not require chemical handling or high controlled environments. Parts are built up as a sequence of (often paper) laminates that are cut and stacked/bonded. Resolution is quite poor and the resultant parts have a heavy, wooden feel which can work well for some parts/prototypes.

Binder Jetting; This technique produces parts that are not as strong as those created using SLA or SLS methods. Binder Jetting uses a powder bed onto which nozzles spray micro-fine droplets of a liquid to bond the powder particles together to form a layer of the part.

Subtractive/Extractive Contract Manufacturing/Prototyping

Subtractive processes remove material to extract a net shape from a slab, by CNC machining with wide material options. This can allow designers to precisely match the material properties required for mass production.

As the CAD files are used to program the cutter type and path used, the engineer knows that the part will exactly match the design. Discounting tool or operator error, CNC machining is precise and repeatable, assuring that two parts will have identical dimensions and properties.

Subcontract (and in-house) CNC machining facilities can provide parts as fast as most 3D printing methods – with the advantage of being able to manufacture from the planned mass production materials, with extremely high accuracy and good surface qualities. Prices for CNC parts out of China are low – but the shipping process adds time that may be more important than cost

Not only can you create prototypes from plastic or metal, but you can select very specific plastic resins which precisely match the material you will use for mass production.

Electronics Contract Manufacturing Prototyping

Electronics contract manufacturing prototyping falls into three stages – each of which is imperative in the correct moment, none of which can be avoided without considerable extra risk;

Proof of concept; use whatever tools, platforms and simulations are appropriate to build the minimum solution that allows you to demonstrate the core principles of the product proposal.

Minimum Viable Product (MVP) execution; You will need to develop a block diagram, a schematic, a PCB layout (the bare board, as GERBER files) and a bill of materials. This family of documents will be linked so the PCBa instruction set can ‘build’ the finished board in a virtual environment that may also include simulation of power/timing and processor speeds.

With these parts done you can either commission a prototype company to supply the finished PCB assembly (PCBa) or get bare boards built and populate them yourself.

Some options essentially force the use of a full spectrum prototyping service – where small frame size SMT (Surface Mount Technology) parts are used, placing them is difficult, soldering them more so! The same is true for many of the FPGA (Field Programmable Grid Array) platforms that are very widely used.

Vacuum casting

Often referred to as silicone moulding, this system casts a silicone rubber mould cavity tool over a 3D printed ‘master’ component and then fills this cavity with two pack polyurethane resin by vacuum charging, to make accurate copies of the master part.

Tools will serve for up to 20 high quality parts, and more if some degradation can be tolerated (for example where parts are to be hand finished and painted).

The urethane parts are strong – and this system can provide a quantity of parts quickly.


It will be very clear to those experienced in product development or contract manufacturing process that prototyping is a multi stage and iterative process that drives product optimisation and manufacturability from concept all the way to mass production and design maintenance.

Proof-of-Concept prototype should be fast – and accepting that this costs budget brings significant benefits in building developer/investor and partner confidence early. Moving quickly can involve using more expensive parts and processes at the PoC stage and this is a good choice – as speed is (within reason) much more valuable than any cost saving that might come from waiting.

Product prototypes should be as closely representative of ‘real’ product as is practical – reducing component costs by using lower resolution or weaker material processes is rarely beneficial in driving the best design process. Build confidence through multiple generations, each representing an important layer of learning as the product evolves.

Custom electronics should be treated as a test of real production – many layers of error can be avoided if the test PCBa is a first draft of the real thing.

Cosmetics are important in many – or most products, so a high standard of finishes can lift a prototype and provide a stronger impression. High cosmetic standards require careful and skilled labour but their value generally outweighs their headline cost by orders of magnitude.

There is always (and rightly) a pressure in the development process to avoid waste – but financial decision makers must reflect on the dangers of requiring restrictive budgets on apparently high headline costs. This can and does generate massively greater waste at later stages in the development. As a common example, buying a low cost FDM 3D printer does NOT mean that the designer’s rapid prototype needs are fully satisfied, forever! Processes appropriate to the type and stage of prototyping will pay for themselves and excessive economising can blow back badly. Nothing builds confidence and assures minimum delays/errors at the later and more costly/inflexible stages like timely and excellent prototyping.

If you have any question or project to run, please just contact Inno manufacturing, we are professional contract manufacturing company for either prototyping and mass production. We are confident with our high quality contract manufacturing service to arise your business.