I have a photo taken years ago, I think at the Newark Kit Car Show, of a 7 style car that had the windscreen side supports made of what looked like a rigid black plastic material of at least 5mm thick. I can make jigs to machine it but need to buy the material in a small quantity to make the bits. Any ideas where to get it or, alternatively, the parts already made.

Polywotsit maybe? Or that horrible bumpy stuff folk use to make internal panels with?

Nylon maybe?

Perhaps these guys could send you some 'samples'???
http://www.directplasticsonline.co.uk/
There in Sheffield so not far from the North East (unless I got you Tinterweb accent wrong??)

Polycarbonae or ABS?
Are you in the northern region?

Yes, just about as north as you can get in England. I am in Carlisle.

The only one I can think of with plastic screen uprights was PTM's Tangerine dream. Chris was a plastic fabricator by trade and used the same 5mm polypropylene as the MK dashboard blanks and interior panels so should be simple enough to get hold of some. ISTR it worked ok, he went to Le Mans in the car a couple of times.

Snap!! I work in Carlisle and can possibly sort you out with some material - send me apm with contact info
atb
Mike