Here are a few more schemes I assembled this Saturday. The first images are of Leonardo's bridge design. This one is not very stable. The large hex/small triangle scheme was a little difficult to assemble due to the way the 4 x 4's lay on one another at the small triangle intersection. The last one is the rectangle scheme I built previously using the 12' long 4 x 4's. This one appears to be much stronger with a lot less bowing. I'm really looking forward to the full build of these ideas!