I was not pleased with the price for Promega and Millipore magnetic separation stands for protein purification ($45 to $377), so I set out to design my own. In this Instructable I will cover the process of making this simple $3 magnetic separation stand using a 3D printer (PLA) and cheap rare earth magnets, which works just as well as the commercial versions but which costs a hell of a lot less. If you are enterprising, you could even convince your PI that a 3D-printer for your lab makes business sense, given the high cost of many small plastic lab trinkets. Print off two 8-position magnetic separation stands and you've more than paid for a RepRap!
Step 1: Print Off the Newest File From Thingiverse
My latest revision of the stand is here: http://www.thingiverse.com/thing:90644
I made it at Techshop (www.techshop.com) on their Replicator 2 (3D printer, in PLA with 3 shells and 35% fill). If you are curious about my design process, here is my first revision: http://www.thingiverse.com/thing:78964 Since then I have gone through different designs, and even an 8-position version! Ultimately, the design included an angled center wall, in order to bring the magnets closer to the sidewall of the 1.5 mL microfuge tube. This increased the speed with which the rare earth magnets can separate the magnetic beads for all your magnetics-based purification needs.
Step 2: Buy Magnets. Insert Them Into the Base.
These 8 mm by 2 mm magnets will hold themselves in the stand by attracting to one another (a serendipitous part of this latest design!) Insert 4 into each cavity/recess (you can easily double up the number of magnets if you bought 8 mm by 1 mm rare earth magnets).
Step 3: Purify Proteins!
This stand is a direct replacement for Promega and Millipore magnetic purification stands (although this stand only accomodates 1.5 mL microfuge tubes) it works at the same speed at which the $45 Promega stand separates the beads. The magnets are easily and quickly removed by smacking the base of the stand on a flat hard surface to release the magnets (they will become attracted to one another; although since they are super-strong separating them and inserting them back into the plastic stand takes a small bit of time). This Promega protocol is a useful primer for those rusty on their magnetics-based protein-purification.