Working on the plastic fantastic Brede, I've been trimming the sheet along joins.
Rather than cut everything to size perfectly, where two parts met, I left one of them oversize and planed it down with this handy little device called "Zip".
Dating back to the 1960's or even earlier, the blade is a single edged razorblade held in place with the wingnut you can see in the photo.
Sadly, the fixing isn't sophisticated enough to allow for depth adjustment, unlike slightly better block planes. Who cares, with practise, the pressure can be adjusted to carve more or less plastic away.
Those little curls mounted up as I worked my way around the boat. I did find that the best way of working was to get nearly to the join and perform the final trimming with a file and sandpaper as it is all too easy to cut too far. However, the speed at which the plane cuts away excess plastic encouraged generous overhangs which made marking out a lot easier.