Rapid prototyping and the production of demonstrators for early design insights


In the early phases of development, it’s vital to gain insights into user needs and preferences to ensure that our designs are not only feasible but also provides a great user experience.

An example product whose ease of use was crucial to its success

This article looks at the tools that Round Peg deploys to obtain substantive user insights and achieve technical gains in short R&D cycles.

The Brief:

This approach requires that clear objectives are set in response to key questions: what are the salient technical risks? Are the technical underpinnings feasible? Which usability considerations are most relevant, and which design best satisfies them?

Assuming that clear, achievable, and valuable (relative to their effort) objectives are in place – a topic for another blog – then we must determine the best way to achieve these aims.

There is always a decision to be made on when to gain insights from mathematical modelling -starting with hand calculations but working up to 3D FEA or CFD, for example – and when to build physical demonstrators to test and analyse. A previous case study explores how we utilise mathematical simulation and testing to overcome design challenges. In this article, we will explore how we rapidly produce physical demonstrators to gain user insights and address technical challenges.

Our Strategy:

What type of demonstrator?

In the early phases of development, it is often useful to decouple your development objectives and create multiple demonstrators. For example:

  • A “works-like” technology demonstrator(s) that shows how the key aspects of the product function to prove technical feasibility.
  • A “use-like” demonstrator that simulates key user interactions; for example, interface, handling, and changing disposables. This should be used in formative user studies to gain user insights and bring clarity to the user specification.
  • A “looks-like” model, or rendered images of how the final product might look. These should be used in user studies/questionnaires to safeguard market acceptance and refine to the user specification.

The three common early-stage demonstrators to show product feasibility.


Designing and producing multiple demonstrators, e.g. a “works-likes” and separately a “looks-like” demonstrator, may seem counterintuitive; classically, making even one demonstrator is a time and resource-intensive exercise. However, multiple demonstrators can allow for more targeted goals which often simplifies the design and can facilitate lower-cost, rapid prototyping methods to enable a shorter overall R&D cycle.

Prototyping decisions

Then we consider the best way to manufacture these demonstrators – are representative materials required? Or is size and form more important? Questions like these clarify the best prototyping method to use. For example, we regularly 3D print both flexible and rigid parts, using either our SLA or FDM printers and have experience with medically approved materials for when a user study requires it. Our experience makes us knowledgeable on best design practices – for example, where to position supports and drainage holes, or the most optimal orientation for strength and minimising warping.

At Round Peg, not only have we nurtured an extensive vendor network for fully embodied design and production, but we also have advanced in-house prototyping facilities. This allows us to make pragmatic decisions on the best manufacturing approach to achieve the quality we need while keeping lead times and costs down.  From 3D printing to more conventional manual tool work and workshop processing, we have a range of reliable, efficient prototyping techniques and means at our disposal.

Our FDM printer and laser cutter in action

For our more classic prototyping methods, such as laser cutting, machining, and sheet metal fabrication, we follow conventional design practices like incorporating rads and chamfers, corner reliefs into nets, and making a note of the order of bending operations. This hands-on experience with multiple manufacturing methods ensures that design for manufacture and assembly is baked into our company DNA and designs from Phase 1.


As is evident from the variety of prototyping methods at our disposal, the effectiveness of Round Peg’s rapid prototyping is closely connected to its versatility.

For some projects, all that is needed are low-cost and rapidly made models for demonstrating feasibility, alongside different approaches to solving the design problem enabling us to get it into the hands of users and benefit from their initial insights.

Usability demonstrator for a formative user-study.

However, and perhaps most importantly, rapid prototyping can benefit the client even when it isn’t a specific deliverable – when our engineers use it alongside the development process it allows them to run several concepts in parallel, iterating the design with physical insights, making it easier to efficiently compare and rank ideas while keeping the design in perspective. This makes for shorter R&D cycles overall and a more cost-effective use of time and resources – benefits that are always handed over to the client.