Aesthetics are important, is it possible to colour match flexible parts?
Sometimes you want more than flexible, you want your component to look aesthetically pleasing. The good news is depending on the process chosen you can have basic colours and colour matching to help you achieve something that flexes and looks good.
RP processes work in layers and usually in proprietary materials. Dressing layers out of a flexible part is not viable, thus if we are looking for a 'step free' part, possibly colour matched, our options are between silicone tooling and PU or tooling and injection moulding. There is a large cost and leadtime difference between these solutions so the answer usually depends upon the maturity of the design. Small runs of PU parts, say 1 - 40 can frequently be achieved in around 10 - 15 days, injection moulding from 12 - 30 days depending on complexity. The properties of PU will not match those of injected grades like Santoprene, but it remains a very valuable prototyping option.