I’ve been having trouble 3D printing the transparent visor needed for my head-up display. The part sent to me by Shapeways was seriously warped and not at all transparent. So I complained about the warping, and they gave me a credit which I spent on printing the visor in white polished plastic.
The white version let me test the form factor (which seems OK), and I’ll glue some reflective film to the inside to check the optics.
If it passes that test I’ll get it manufactured properly. I’ve found a local prototyping firm who can make the visor using CNC and mirror-coat it using vapour deposition. Not cheap – we’re talking several hundred dollars – but it’ll be done properly.