Small suggestion to any DIYer
A possible work around drilling ovals is to:
A) If you already have a thumb you like, buy a thumb mold making kit
B) Buy a oval vinyl slug and use instead
C) Buy an oval vinyl slug, and mold that to get urethane feel (if anyone does this, carefully cover slug with scotch tape and then mold. Vinyl material and silicone mold don't like each other.
For small amounts of plugging material, can use smooth-cast 300 series. I have used this and actual bowling ball plugging plastics, it's the same thing. But smooth-cast will only save you money if you need small amount.
Smooth cast has both urethane material you can plug ball with, and silicone molding material. If anyone wants to DIY thumb mold, I've used both smooth cast silicone and the molding silicone they sell for bowling. The smooth cast silicone is much easier to use, and far cheaper. A trial kit costs like $30 and that's enough to make many molds if mess up.
By the time I was done with my DIY ball press and jig, that cost hundreds. But I saw no other option if I wanted to actually do this at home, in my limited space and not spend thousands.
I actually don't really recommend people build their own drill press unless they are crazy (like me), it took me 8 months to design and dozens of hours to construct, but at least now I can drill anything I want to within 1/16 pitch accuracy. But there are many videos on youtube of how to make your own drill press, and then can buy a jig.
To save on drill bits -
first drill a small pilot hole, then use a $3 spade bit. (although they don't make 31/32 spade bits). This will work for slugs or the 7/8 diameter grips.
Of course an actual bowling ball drill bit works better. I've done the above with spade bits, but did eventually buy all the bowling drill bits I need.
