Depends on how much material needs to be removed? If 1/4” or less needs to be removed, I use a 6” rotary hand sander with 60 grit disc.. If more material needs to be removed, I use a 3” carbide disk and then trim to final fit with disc sander. I sand the inside of the canopy that will be glued down, with 40 grit sandpaper to give the bond tooth! I use epoxy with chopped cotton to thicken the mix. I mask off both sides of the canopy and hold it in place with 3 or 4 bungee cords + small wooden blocks at areas that don’t want to lay down flat. Mask off the fuselage side, also..........a few minutes spent in preparation will save hours of re-do! Fill and sand until you get desired fit, then re-mask the canopy out about 1/8” for final painting. Recommend canopy be glued on with shop temperature about 65 degrees Fahrenheit, so that canopy will close on the ramp when it’s 100 + degrees and still won’t leak too much when the temperature drops below zero degrees, in that wave you stumbled upon!
Hope this helps,
JJ