How do I drill my own handle materials for these kits?

Get a 1/16, 3/32, and a 5/32 drill. Use the 1/16 drill to drill your pilot hole through the liners as a template, with the handle material butted up against the bolster and clamped to the liner. Then, remove the handle material. Drill it through with the 3/32 drill. Lay the handles out right and left. Then, drill with the 5/32 drill x 1/16 deep. Your screw will then fit and be counter bored for the screw head.