Newly finished DIY stirplate for yeast starters. This was just a quick test run, with water. Once I completed assembly, the magnets were slightly too close to the stir bar, so I'm using the towel as a thin buffer. I'll have to alter the design a bit to correct this.
The entire stirplate was made for roughly $20, using parts harvested from an old computer (fan, rare earth magnets), an old digital camera charger, plus additional store-bought electronics (rheostat, rocker switch, etc). Fun weekend project. I found all the necessary instructions here - is.gd/aNql0