If they have any thickness to them, I use a router table(s) - the "poor man's laser cutter".

Make one really good template out of 1/4" ply, then tack glue a stack maybe 1/2"-3/4" high (too high and the stack starts to get tippy). A straight trim router bit is what you want. I've found the templates seem to last a bit longer when the edges are hardened with CA.

The smallest I've seen is 1/4" diameter which is OK for typical spars notches, but dulls fast and tends to tear out a lot. I have a couple of router tables with different diameter bits.

Normally, I'll rough the stack on a bandsaw to within about 1/16" of the stack, then use the router to finish what's left. This makes the router cut a lot easier as less wood is being removed. For lightening holes, I rough them with an ancient dremel scroll saw because the blade is removable and lets you get into the center of a lightening hole by drilling an access hole.