A simple sketchup for making custom combs for electrophoresis such as PCR.
If you download the script and open it with OpenSCAD, the third to last line is commented out for the ability to export 2d projections of the design (dxf).
This is useful if you wish to laser cut out the combs.

Since most combs need to be thin, it is recommended to laser cut out or CNC engineered plastic (acetal delrin or polycarbonate are two good choices).
Default spacing in this script includes standard 8 channel pipetter and 1/2 8 channel for loading every other well.
Our eletrophoresis chambers support 21 teeth with 8-channel spacing.

Once cut out, you just mount these combs to a rigid spine (to flatten them out) and drop them down to the bottom of the gel. This can be done with anything from binder clips to screw mounts. The two side "wells" are to keep the remaining ones a constant depth.

First set of testing results:
As long as the spine holds the material flat, it works very well even down at 0.5mm gap between teeth. Loading the wells can be difficult at the current dimensions of the well (because it is roughly the width of a pipette tip). 3x and 2x 8-channel spacing were tested at 1, 0.75, and 0.5mm gap between teeth (1% gel).
Well depth spacer from the bottom should be reduced to 1mm (defaults to 2mm) to require less gel.