The hot wire goes from the c-clamp on the overhanging arm, straight down through a hole in the table to a screw on the underside.
My friends liked to cut yellow, brown, and other foam with it, but that's crazy.
Why breathe poison gas if you don't have to? The blue and pink fumes are bad enough.
Now I prefer to use an old carpenter's saw to shape foam, followed by sharp new sandpaper.
But some people just love the hotwire.
Step 1: Not Much to It
When protesters burn tires there's a lot of that stuff around.
The wire elongates a bit when it gets hot. The wooden leaf spring at the top keeps it tight. Nitinol wire shrinks when hot, so that's not a problem.
The electronics consist of connecting the cutting wire across the output of a 24 volt transformer taken from a dc powersupply. That transformer is plugged into a variac plugged into a footswitch plugged into an isolation transformer.
Some wires have higher resistance and get plugged directly into the variac.
That's why that second isolation transformer is there, to make it a little harder to electrocute yourself.
This table also has a skilsaw bolted to the underside to use it as a tablesaw for cutting wood and aluminum.
If none of this vocabulary is new to you, you can figure out the safey issues yourself.
Stay healthy and safe.