I've done a few with the my electric fillet knife, it works well...but I find holding the knife perfectly perpendicular to the surface the biggest challenge. And when you try to clean up a spot where the knife wasn't level, it looks like hell. Before I cut the foam on my new cases, I think I'll try to rig up a hot wire type cutter, watched a few videos on YouTube on how to make them...seems pretty simple and gives a perfect cut.