Reply by EarlS

I think I would go with a loose tenon, that is, a rectangular dowel that has had the edged rounded off. The accompanying mortise would be made using a router (see the Leigh mortise and tenon jig). The problem of sharp corners that would be week points where the stress/load would cause the wood to break would be reduced/eliminated.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"