You can see the little 1/72 Polikarpov I-152 that I bought from Squadron in another post on here in general modeling discussion. It comes with a vac-u-form canopy and a few detail parts. I’ve never done anything with vaccuum formed stuff before. It looks likes they took a clear plastic sheet and press some sort of mold to make the shape. Do you cut it out like photo-etch? Saw it?
I have a small pair of surgical scissors that I use to cut out the canopy from the carrier. Many modelers use an X-ACTO #11 knife blade. In either case, I find it best to leave a little of the carrier & then slowly sand it down to fit. Work slow & do lots of dry fitting.
Regards, Rick
I also like to stick a clump of blu-tack or modeling clay behind it for support while I’m cutting - it helps keep it from splitting and also makes the lines easier to see.
I used both of the techniques mentioned above a few weeks ago for my first canopy. They worked extremely well!