Now there's a good idea. U-joint caps are made of some pretty tough stuff. They have to be. They'll certainly hold up to whatever a 2 stroke can put out and they can be smoothed and painted or even polished with the right compound and bench buffer.Sometimes i use a u-joint strap. Very strong and never had a problem using them. You can get them in just about any size you need at a good auto parts store.
The trick might be finding a parts counter man patient enough to look through his stock or let you do it. Today if you don't have the make model and year of the car most counter people can't find anything.
Tom