Similar stands for protein purification from Promega and Millipore cost anywhere from $45-377 (for 8 position stands). That's ludicrous! It is plastic with a neodymium magnet inside. So I designed my own and printed it out in about 25 minutes (total cost around $2, including the rare earth magnet inside). The stand is sized to fit two 3/4" x 1/2" by 1/4" rectangular magnets, although the space should accommodate and work perfectly with other smaller/rounder rare earth magnets. It is also designed to be modular, in that the first prototype here fits together with tape, such that you can transform the two-position stand into a four-position stand by removing the tape.

I am happy to hear your comments, questions, and to see if anyone else can derive a better unit. I plan on quickly designing an 8-position unit sometime in the near future (per request, to replace the Millipore unit).