This trick will get you up and rolling easy and cheaply slicing into plastic "like a hot knife through..... uhm plastic!"
I warn you this is pretty dangerous, we are talking about a Exacto knife(SHARP), and a soldering iron(HOT). there is possibility of both burns and cuts! (and possibly burned cuts!) Please use it with care! but if using it carefully, I think it could be safer than trying to do the same things with a sharp knife and pressure.
I first ran into mention of such a thing from a guy who rebuilt battery packs for laptops. he would slice open the old one, then replace the bad cells, (or all of them) and then glue it shut.
But its useful for cutting vinyl. for cutting rayon or vinyl cloth, plastic coke bottles. packaging. It could probably also be used to carve plastic or wax , but i suspect the end result would be a bit globby/stringy.
Step 1: Parts!
one pencil type Soldering Iron (between 25 and 25w) Preferably one where the tip can be removed via loosening a screw on the side, (see photos)
That's it. (might need some wire cutters, pliers, sandpaper, I didnt.)