I recently purchased a used (... "previously owned") Spyderco Tenacious. A great knife at the usual $45 or so full retail. This one set me back $25, but it has me thinking about trying my hand at making some custom scales. The least expensive "ready made" custom scales I have seen online have been $35 for the set.
For $13 or so, you can get a 3x12x1/8 slab of Micarta (enough for two knives).
You can also consider 3/16 or 1/4 inch thick material if you want a fatter and rounder handle.
So I placed the order at USA Knifemaker for a pair of 1/8 and a pair of 3/16 black canvas micarta. Grand total including $3.39 shipping is $7.90 -- so the scales will end up costing $4. At that price I don't mind having some extra material either as a backup in case of mistakes or just to experiment with.
And it is a good idea to experiment with hole drilling on some of the scraps (or sections that will be scraps), especially the countersinking.
Also if you move to G10, use a respirator for sure. G10 can be cut on a diamond saw wet to avoid a lot of dust.
Pins - they hold the handle. Epoxy is more to provide a "seal". Nickle silver, brass, mosaic, copper. Loveless and Corby bolts (Corby can be tricky as to thickness).
Small Holes - 3\16 -- I measure 0.188 (over 0.1875) Lanyard Hole - 1\4 -- I measure 0.248 Large Holes - 3\8 -- I measure 0.390 (over 0.375)
Feedback? Questions? Drop me a line!
Tom's Knife Info / firstname.lastname@example.org