JBD - I've been seeing more of the ladder design (e.g. Spacewalker) and assumed the internal spaces were cut out of the block. This closeup though looks like the cross beams are inserted. Are you using balsa or basswood? Are you securing with CA glue or wood glue? I typically use a full balsa insert so I'm wondering if the cross beams are enough to reduce torque/vibrations?
Balsa with CA glue, I never have a problem. It just like a laser cut car but not as neat. I have 3 ladder cars I have built myself start to finish. I
The only thing I like about them u can add a few more cubes of weight.