Reply by JJohnston

I don’t think those Grizzly two-hand sanding drums will work for this. You’d have to have one hand inside the tube. It may work near the ends, but not in the middle.

I second the router recommendation. Concentrate on making one good hole in a piece of plywood or MDF, then use it as a template with a bearing-guided bit to finish off the others.

-- My broker promised me he would treat my money as if it were his own. Trouble is, he did.