OK, good info, especially the drilling perpendicular to the grain part.

I found some Mahogany blocks left over from a prior woodworking project that should work. That should be strong enough, but I'm worried that the silica content in the wood might not be the best? I don't plan on putting anything other than unpainted tubes in the blocks.

I was planning on drilling the holes in my drill press and then cutting the blocks in half in my band saw...the blade is much thinner than even my thin-kerf table saw blade (I do a lot of woodworking), but would that still be too thick, and would I risk crushing any tube that I put in it?

Thanks,

Pete