I made two templates, one that I drilled holes big enough to fit the B&C switches (15/32 if I remember correctly) and the other with just #30 drill holes. The #30 hole template will be used to drill the panel.
One side of the template has right switches and opposite side of one template has the left switches laid out.
Template laid on the left side.
Right side switches and layout. There are spares on each side.