your grinder or multitool will bounce off the surface and mark the acrylic as your’e trying to get a start on it!
dremel or nothing for me .
yep thin cutting disc. no vibration . will fly through 4mm acrylic. I also fear a steel multitool blade would heat up and want to stick itself to the plastic.Might be an excuse for a new tool then. What is about the Dremel tool you like for this type of job? I haven't used one before but I'm guessing they would be less aggressive with the cut? Would you use one of the thin cutting discs or any other bit/technique?