If you are into arts and crafts cutting foam is a great simple way to create some interesting projects. By running high current through a light gauge wire is a great way to burn down your house if it is wiring in your walls but if this wire is a bare piece of wire when it gets hot it is a nice way to slice through some foam. The shorter the piece of wire the lower the resistance, not sure I would attach a piece as small as was connected directly to the lantern battery but it didn’t explode into a million pieces of acid so I guess all is good. In the final design the dimmer switch is used to adjust the amount of power the 12 volt transformer outputs. When selecting the dimmer make sure it is designed for transformer loads since most dimmers simply chop out some of the sign wave which can cause transformer damage. It would be best to install it into a metal switch box also for safety.
The rig looks great and is built from inexpensive materials so it would be simple to adjust to fit your requirements.