"jeff" wrote:

Last fall I drilled several small holes, about 1/4 inch, into the
hollow, sacrificial keels of my cat. I was exploring for water
which has been known to get into the keels, but found none.

Now I have to patch the holes.

Drill the holes to a common size that will be the same size as a pilot
drill for a coarse thread sheet metal screw or a lag bolt. 3/16"
pilot, #14 screw, 1/4" pilot, 5/16" lag bolt, 5/16" pilot, 3/8" lag
bolt, etc.

Screw the above into, then back out of the hole using the bolt like a
tap to create a threaded surface in the glass hole.

Blow out dust in hole or clean threads with acetone.

Mix up some epoxy resin and slow hardener thickened with
micro-balloons to the consistency of glazer's putty, then plug
threaded holes proud.

Let cure 2-3 days, then sand flush and paint to match.

Have fun.

Lew