What material for Risers?

[FishStretcher]

One more thing- don't put plywood in your floor. Use a real foam core if you can, or coosa. Or buy nidacore- premade from boatbuildercentral.com.

Barring that, then balsa core.

These are all ok for weight. The foam cores are lighter, as is the nidacore.

Balsa seems to be stock. It is strong, but it is wood. And it gets wet and rots.

Plywood is the worst. Heavy. Strong where it does no help. Grain orientation makes for a faster rotting process than balsa when you get it wet/ drill holes.

I think you should check out 3/4"-20mm nidacore first. With or without glass already on it.