I have a bunch of M3 screws I needed to cut down and was struggling with my Dremel. I took Kando_G's screw support and modified it in TinkerCad to accept a 10mm x 5mm, M3 brass threaded insert and filled all the other holes for strength. I put a couple of nuts on the exposed threads of the bolt I'm cutting to absorb some of the heat produced while cutting.

I use a soldering iron to melt the brass insert into the hole