anybody know the size?

Just measured the hole on a three ply bass drum (badge and grommet are missing) and it is 9/16ths" in diameter. Grommets on these were held in place by friction (they did not go into the interior of the drum nor were they crimped in place) so they would have to have been very near the same size.

I needed one years ago but ended up having to make one.

Thank you KO! I did the same and came up with just about 9/16 as well.

How did you make your gromment? That sounds interesting.

Brass tubing and a flaring tool like they use to make brake lines. A double flare is very similar to the flange on a standard drum grommet. There are some videos on youtube about how to make double flares and you can get the tools at Harbor Freight although I think 1/2" is the biggest size that will accommodate. The one I made for a Gretsch bass drum was a long time ago and I did make it so I could crimp it over inside the drum. Not factory correct but I didn't want to lose the badge.

Wow. Youre a better man than me! I'll just have to find a grommet that will work.

And an old chair with tacks.