A knife can be a clumsy tool when it comes to cutting plastic. Whether you are making some simple cuts to your plastic model parts or attempting something more difficult, there is a better tool for the job. A hot knife can combine the cutting edge of a knife with the heat to reduce plastic to the consistency of butter. By building your own hot knife, you can give yourself a faster, more precise tool.
Place a soldering iron tip on your work table. Hold the base of the iron tip in place with pliers.
Hammer one side of the soldering tip flat until you get a cutting edge. This will be your hot knife blade.
Place the converted soldering tip into the end of the soldering iron and turn on the soldering iron.