If you want to print this page and cut the template out, make sure both these lines are 51mm (or 2”) long to confirm correct dimensions and proportions. If different try Resetting printer scaling to: None (no Scaling or resizing). You can also make allowance for any difference using the dimensions shown on the diagram.

Measure the depth of your control cavity to be sure the parts will fit comfortably.
The cavity must be 25mm (1 inch ) wide, if narrower than that it will have to be made wider using a Milling machine for cutting control, or less desirably a fence-guided Router.