6-Fold Plaques from Triangles

Here are four decorative plaques and the triangular based motifs from which they are constructed.

Six copies of a simple motif are rotated, each by a different multiple of 60 degrees, around a common axis. The six copies are then combined with openSCAD to form a plaque with 6-fold symmetry.

Seven stl files are provided, 3 simple motifs, and 4 sixfold plaques:

motif_11.stl a simple motif made of 11 triangles
motif_12.stl a simple motif made of 12 triangles
motif_18.stl a simple mot