A magnetic stir plate is used to mix a liquid. It's magnet spins around and makes a metal object in the liquid create a vortex to mix it. This project cost me $20-25 but could be more if you don't have some things that I had lying around. Please vote for me!
Step 1: Parts List
You will need:
A computer fan,
A container that fits your computer fan,
2 9-volt batteries,
2 9-volt battery snaps,
Knob that fits the center rod of your potentiometer,
Magnet (I used 3),
Piece of metal like a nail,
Optional: soldering iron and solder.