I use the tools made by Hot Wire Foam Factory. https://hotwirefoamfactory.com/
The hot wire melts its way through the foam and leaves no particles to clean up afterwards. Below are photos of a tunnel that I constructed for a client in California several years ago while I was still in the model railroad scenery business. The substructure of the tunnel is made totally from pink insulation foam of various thicknesses. All of the foam was cut with the Hot Wire knife tool. The slabs of foam board are held together with a specialized glue call "Foam Fusion" sold by Hot Wire Foam Factory.
I engraved the stones in the tunnel portals using the scribing tool.
Below is a photo from one of our York show booths showing a partially finished tunnel with exposed foam.
Below, are two photos on the bench in our shop of a north woods diorama, that I made for a client. All of the terrain is carved from pink insulation foam.
This a great way to cut foam with no residual mess. However, ALWAYS cut in a well ventilated area or outside on a sunny day. The vapors from the melting foam are highly toxic.
