Hand machined mechanical pencils

Laser-cut transformer bobbin (07/09/13)

I needed a big DC choke so I built one around a gapped microwave oven transformer core. For a bobbin, I used the box-jointing trick on the laser cutter to make one from 3mm hardboard which was subsequently glued together. Worked pretty well.

Here's the cutting profiles I used, to give an idea of the tab locations.

Quick video of assembly: