This seemed like the best category for this topic, if it needs to be in another, feel free to move!
I built a Magnetic Stirrer the other night with spare parts I had laying around the house. Very easy and only took about an hour!
Its not necessary I know, but its fun and makes testing your water a tad easier.
The parts I used are as follows:
1 80mm case fan. (from an old power supply.)
1 set of 4 case fan screws for attaching the fan. (Already in the fan)
1 12vDC Power adapter.
1 USB HDD case.(Old USB1.0 Case)
1 Tube of strong glue. (I used epoxy)
1 Roll black electrical tape.
1 Rare Earth Magnet. (I got this from an old hard drive.)
I would base this project an intermediate level task due to the electricity involved, possible fire hazards and risk of electric shock could occur.
Making the case for you stirrer is up to you too decide, and there is countless possibilities for design. Once you have obtained your materials and have and idea for your case start building!
If anyone would like more detailed instructions, I'd be happy to provide them. If not I'll save myself all the typing and go swim!
Best of luck!
P.S. Heres some pics of the finished product!