These are extensions to the Zometool
system. The struts fit into the pentagonal (red-axis) holes of a standard Zome ball.
The struts are not colored maroon when printed. You can paint them with acrylic paints, dye them (if you print in white), or use heat-shrink tubing to achieve certain colors.
Many 3D projections of 4D polytopes require olive, lavender, and maroon struts.
The video below describes the general process used to create such models in vZome