Prototyping techniques

How closely the prototype resembles the finished product — in appearance, in materials, and in whether it actually works.

It is fast and cheap, so many ideas can be tested; and users criticise a rough model honestly, because it is obviously unfinished.

It is slow and expensive, so few can be made; and the team and users become reluctant to change something that already looks finished.

They explore ideas, refine them, and communicate them. Each job suits a different kind of drawing.

Informal (freehand sketch): fast and disposable, so many ideas can be explored. Formal (isometric, orthographic, exploded): unambiguous and to scale, so it can be manufactured from.

All three axes are drawn at 30° to the horizontal, and nothing gets smaller with distance — so measurements stay true along each axis.

Showing how a product assembles: the parts are separated along the axes they assemble on, in order, so sequence and every component are visible at once.

To answer a question about the design before the product is committed to — testing an idea, gathering user feedback, communicating the design, and finding problems while they are cheap to fix.

By the question. Anything the body judges (weight, grip, texture, fatigue) needs a physical prototype. Comparing many variants, or examining forces inside a part, suits a virtual one.

Comfort is a felt response to pressure, texture, temperature and time. A model can give mass and geometry, but none of those is an output of the simulation.

Scale, aesthetics, materials, function and performance.

As the mechanism alone in a rough open frame. It is quick to build, and testers comment on whether it works rather than on how it looks.

So the comparison is fair. If the shapes differ, any difference in feel, stiffness or finish could come from the shape rather than the material.

What happens over time — wear, heat, fatigue and the failures that only appear after thousands of cycles.

A surface model defines the outer skin only, used for complex curved styling. A solid model defines the whole volume, so it has mass, a centre of gravity and material properties, and can be analysed or manufactured.

The designer supplies constraints — loads, fixings, material, allowed space — and the software produces geometries that meet them, often shapes a designer would not have drawn.

Divides a part into many small elements and predicts stress, deflection and where it will fail under a stated load, before anything is manufactured.

All three simulate USE rather than form or strength: reach and clearance, being inside the design at full size, and force feedback on a virtual control.

Creating physical prototypes quickly, straight from a CAD model, so potential users and design teams can interact with them and give feedback that drives development forward.

A laser cures liquid photopolymer resin layer by layer. It gives the finest detail and smoothest surface of the three, so it suits appearance models. Parts are brittle and need supports.

A heated nozzle melts thermoplastic filament and draws each layer. It is by far the cheapest and most available, but has visible layer lines and is weaker across the layers than along them.

The part is built inside a bed of loose polymer powder that the laser fuses selectively. Overhangs rest on powder already present, so nothing has to be printed to support them.