Drill oversize holes- fill with epoxy - how ?

[RS]

I'd whet out the inside first with unthickened epoxy using anyting handy (q-tip, small brush, etc.)
Then use a meat infusor to inject the cabosil mix from the back of the hole forward, withdrawing the needle as you finish injecting. The infusor looks like a big hypodermic syringe with a plastic needle. They are about $4 at X-marts.

Tape over the hole until it first sets. You can use a putty knife to scrape it level while it's a little soft.