If you have to work with polystyrene, you will need a qualified helper

The greatest support when working with polystyrene
Some people wonder why a thermal knife should be used, they do not speed up the work and we will cut foamed polystyrene with an ordinary knife or any saw blade, and a stubborn line will do the trick. It's just that it's not about fast cutting of polystyrene because cut with a thermal knife material obtaining smooth and perfectly even surface cut. And an additional plus of such cutting is that we will not be overwhelmed by the side effects of this cut, i.e. balls imitating snow everywhere. The knife is very easy to use, just plug it in and wait a few seconds for it to heat up.
I present to you a helper for hot cutting
Xtreme 2991 is a set ideally suited for cutting foamed polystyrene , you can use it for professional preparation of polystyrene or for decorative molding. Great for renovations and hobby crafts. The temperature is set perfectly for cutting foamed polystyrene, cut straight , clean without the slightest bumps and will do without further onerous cleaning of residual polystyrene
3 tips to choose from: needle, cutting tip, engraving tip.
