Grab your monocles. Version 2 features a driven wheel lined with magnets to attach tube adapters, and he’s modeled 50mL and twin 15mL tube holders. The attachment points look like a simple ...

Shake the filings into the long thin section of the tube. Magnetize the filings by stroking a magnet the length of the tube several times. Use a zippy magnet, a 1/2 inch diameter NdBFe magnet works ...