Thanks for your speedy reply.My results will take a lot longer,and there may be more quaestion before completion.

I`ll keep you informed. Thanks again,Brian.

An advance warning: this is totally back-of-the-envelope scribbling, so no guarantees.

Consider the origami struts. As three come together at each point, they should be folded at 60 degrees…the cross-section is, effectively, an equilateral triangle with open side. A strut is folded from a piece of paper with original proportions of 1:3; after folding, each face will be 0.25 of that ‘1′, so the ratio to the length will be, then, 1:12. So, how far is it from the fold to the center of the open side? Calculating the height of an equilateral triangle gives us 1 * 0.5 * sqrt(3) ~~ 0.86. So, the ratio of that distance to the length of the strut will be something along the lines of 1:13.95 ~~ 1:14.

Assume, for sake of argument, that you’re fitting your struts together with an edge (rather than a face) along each edge of each tetrahedron. The diagonal cross-section of a strut will be 12mm * sqrt(2) ~~ 16.97mm ~~ 17mm. This might lead us to conclude that a good strut length might be 238mm. On the other hand, if you’re fitting the struts with a face along each tetrahedral edge, 168mm might work.

There are a lot of probably faulty assumptions (not to mention dodgy math and worse geometry) in there, and when combined with the differences in tolerance between wood and paper….I’d recommend cutting your pieces long and sticking them together with putty at the ends while you’re fitting things together…trimming would be a much better prospect than gluing.

Please let me know how it turns out (and what strut length turned out to be correct).