I make custom pickguards on a regular basis. here's my typical workflow ...
1) design the pickguard on the body (easier for a customer to visualize the rounded edges) being careful not to leave impressions or graphite marks on the wood
2) make a paper template and position it on the finished body, massage if needed, secure client buy-off
3) make a wooden template by tracing the pattern, cutting it out at the bandsaw, and detailing it with an ascillating drum sander and sanding blocks
4) double stick tape the pickguard blank to the template and use a template bit to cut the perimeter.
5) use a home made 'pin router jig' to cut the pickup holes. I went this route because of the very small corner radius needed for may pickup shells
6) use a chamfer edge router bit to add the edge detail (the angle I use varies by pickguard design and material thickness.) once removed from the template, I use various grits of sandpaper to detail and buff the beveled edges
7) I then drill the mounting holes and countersink them with a bit that matches the angle of the mounting screws
8) the completed pickguard installed
all the best,
R