Have you resolved your windscreen material yet? If not:
A couple of thoughts; one, polycarbonate is hydroscopic, so you should be able to dye it yellow after drying it out in an airing cupboard for about a week!. Actually, 3 thoughts. You don't mention what thickness you require, so I assume in the region of 400microns/0.015", which is packaging grade - Ring round the packaging sheet suppliers for samples for the "Transparent boxes in which you plan to sell your models" (likely to be PVC, PETa or PETg; or even old fashioned celluloid). Ski goggles are made from UVEX, so replacement "lenses" are easily available, and available in all sorts of colours, but if only transparent is available, it too is hygroscopic and susceptible to dying. And there's more.... Architectural and industrial modelmakers are a useful source of offcuts, particularly if you can offer a quid pro quo, as you clearly have considerable skills they could use.
I can't recall the generic name for UVEX, but in its raw sheet for it smells like camel's piss, I think it is Cabulite.
All these plastics are thermoformable so, if drying them, don't get them too hot as they start to distort over about 60C, and ideally the PC and UVEX should be dried by forced air convection for a few hours, but this is usually impractical in a semi-domestic setting so lengthy drying is the alternative - remember, the drier you get them, the better the uptake of dye. About 7% would be the uptake, so strong dye over a couple of days.
Edited by Bloggsworth, 16 January 2011 - 10:53.