hrst's answer was very thorough. I can add an example and a couple of comments.
I've been working on standardizing my workflow. I love experimenting and playing, but ever since I finally, really got it that handmade emulsions are up to the task of serious photography, I only want to be out and about with my cameras. That means getting serious about darkroom quality and efficiency. I've made up six identical 5-inch emulsion coaters with 4+ inch /11 cm wells. On film, that makes an almost 5-inch path. I'm using them for film for my WP and every size down, including roll film. That size path is perfect for two rolls of 120 or three rolls of 127. In the attached Whole Plate photo, you can see the fall-off on the edges. The film is 6-3/8 inches wide with a good 5-inch path of emulsion, plus selvage edges. You could either cut off the selvages for smaller formats, or as I'm doing with my WP, incorporate the edges into the final print. By cutting the width to the final format, before coating, I only have to make one cut to length after the emulsion is dry. I do cut off the selvages for roll film. The thinner roll film is easier to cut than the thicker sheet film.
A good method for cutting roll film is to take a roll of commercial film, with a tiny bit of the width trimmed off, and attach it to two pieces of aluminum frame (Nielsen type) with foamcore board holding them apart to the right width. Clamp at the top, hold firmly at the bottom, use a sharp X-acto blade, and perfect film each time.
Acrylic is very hydrophobic. If you want to use it, I'd love to see you develop a good subbing formula/strategy. I hope you do and have great luck.