I don't like having to continuously swirl my test tubes while doing water tests & the lab grade shakers are too expensive. So I made my own.
Parts list:
-Small styrofoam box
-Knife
-A umm... "retired toy"
-Make a small hole in the box that the innards of the "toy" will fit into.
-Make an indent in the top of the box that will provide a tight fit for a test tube.
-Done
I can't find my soldering iron right now, but I eventually plan to put a switch on the side & clean things up a little bit. But for now this will suffice.