Make a paper template of the chassis base.

This is a regular hexagon with a diameter of 300mm (the radius and each
side is 150mm)

use the template to cut out 2 chassis panels.

NOTE: use the same template to make both panels. clamp them together and
trim this to shape as though it is one panel. Do not unclamp the panels
until you have marked them so that they can be re-assembed into on piece
(mark them with a key)

Use some scrap polycarbonate sheet to practice makeing wells.

NOTE: this drill bit originally had spurs. The spurs were ground away to give a flat profile.

drill holes into the well so that the servo wheel can be anchored to the
chassis

Trim the end of the screw using a pair or wire cutters

The trimmed screw will have a rough sharp end which should be smoothed.

Use a small piece of 0.5mm sheet steel to make a guard.

Drill a hole in the guard the same size of very slightly larger than the
screw.

Place the guard over the screw (the screw fitting through the hole)

Use a small grinding wheel on a hand drill to grind down the screw end.

Be careful not to let the grinding wheel slip off the guard otherwise
the finish of the chassis plastic will be spoiled