Use Tamiya spray number TS-71 (smoke). Works great if you do it right. Mosy hobby shops carry it.

1. Wash the canopy with dishsoap and water real good. This is very important to get a good even result. You have to get off the release agent that is still on a new canopy after it is made. You can't see it, but it's there. If you do not get the release agent off you will end up with a splotchy job. This is important no matter which product or method you use.

2. When spraying avoid the temptation to put to much on at once. Go with very very very light coats and you will be a happy camper.