How do you make seat belts?

The belts can be created with thin paper, e.g. paper from a cash register. Cut this in small strips, wide enough for one belt, long enough for all belts. Paint the belt with the required colour. Using gloss-paint will give the belts a kind off semi-gloss look. Flat paint of course makes them flat. For the hardware you can use aftermarket PE racingbelt hardware.

For road cars you can use the metalfoil you very often find on winebottles. This foil is very thin, has a metal look (on the inside) and is pretty strong. Because it\'s strength you can give it the correct form, cut it in to get the belt through the cut and make a little hole in the 'lip'. The plastic part where you put the buckle in can be made of a small piece of plastic sheet. Just cut it and paint it is enough to make it look like the real thing!

For me this works very fine to get realistic belts.
(Thanks to-Xander Pikaar)