After the TECHNIC Meta-Parts, let me present another article
from Kevin Knuth at BrickEngineer, which describes us some good
examples and techniques to build triangular and hexagonal
structures. His designs below, show equilateral triangles (equal
side lengths). These are extremely sturdy constructs and the
smallest possible ones are just below, together with the parts
required to build them. If the pins are a bit clunky on the left
triangle (any size triangle can be built this way), thin TECHNIC
liftarms with 2L axles can be used to secure the triangle
(middle and right images) Following we have similar but larger
versions of the last triangle. They have however slightly
different forms. The left one uses 11L beams with 1L offset, so
that there are peg holes at the triangle corners and the version
at rigth uses 9L beams, but lacks holes at the triangle corners.
The example below, shows a 11L triangle with an axle at the
center, made with a TECHNIC 3-blade rotor. The animation
illustrates how the braces hold