Wallpaper group p4

This is part of a set of 17 things representing all wallpaper groups, designed for learning about symmetry.
"A wallpaper group (or plane symmetry group or plane crystallographic group) is a mathematical classification of a two-dimensional repetitive pattern, based on the symmetries in the pattern. Such patterns occur frequently in architecture and decorative art, especially in textiles and tiles as well as wallpaper."
https://en.wikipedia.org/wiki/Wallpaper_group
This thing includes tiles for creating patterns with the appropriate symmetry.
The tiles have an embossed swirl pattern that is helpful for observing rotation, translation, reflections and glide planes.
Straight edges indicate mirror symmetry.
Files:
p4-cutout.stl - the asymmetric unit.
p4-cutout-swirl.stl - optional insert for the asymmetric unit.
The figure shows the symmetry elements for this group.
OpenSCAD files are available upon request.
Wallpaper group p4m has four tiles per unit cell.
The group p4 has two rotation centres of order four (90°), and one rotation centre of order two (180°). It has no reflections or glide reflections.
Orbifold signature: 442
Coxeter notation: [4,4]+
Lattice: square
Point group: C4