Magnetic base (Compact On/Off Magnet)

This design is a compact, switchable magnetic base compatible with a variety of printed tools i designed including a phone stand, a camera stand, a vice and various translation stages. It can be used to place a phone or camera on any magnetic surface, a sample on a microscope plate or a device on an optical breadboard. This design uses cylindrical magnets 12 mm wide and 3 mm thick. There are two versions using respectively 10 and 20 magnets. It also uses 1 mm thick, 12mm washers. The washers should have a center hole as small as possible, M2 washers are best, M3 also work. Do not use stainless steel washers as they are not magnetic. Nickel plated of plain steel washers work best. Of course if you have 12mm steel bars at hands, using 3mm segments will be even better, i used washers as it is inexpensive and easily available. Besides those you will also need 4x 12mm M3 bolts with nuts and M3 melt inserts 4.2mm OD, 4mm thick. Detailed assembly instruction are available on instructable. 

If you want to use this base with my modular 3rd hand system, you can use the "Adaptor for modular lab holder system" part. If you cannot or do not want to use melt inserts i added a version of the top casing adapted for M3 nuts. However i find this option less reliable. While testing, the small magnetic base with 10 magnets was able to suspend 3.6 kg upside down. The larger magnetic base with 20 magnets was able to suspend more than 5kg and was not tested to its limits.