Here are four more cat coasters based on the 17 plane groups. See Cat Coasters 01 - thing:54736.The four plane groups are: cm. pmm, pmg, and pgg. The number of symmetry elements increases as we procede through the plane groups. These groups contain combinations of reflection lines and glide reflection lines. The four sets of files for dual extrusion are:cat_coaster_cm.stl and cat_decoration_cm.stl cat_coaster_pmm.stl and cat_deocration_pmm.stl cat_coaster_pmg.stl and cat_decoration_pmg.stl cat_coaster_pgg.stl and cat_decoration_pgg.stlCat_coasters_02 scad created the stl files and the images are in coasters_dxf_02.zipThe coasters are 110 mm in diameter and should be constructed directly on the build surface. I used one shell and ten percent infill and the coasters printed in about two hours.The coasters can be used as teaching aids. Pdf files that show some of the symmetry elements are included in coasters_dxf_02.zip. Reflection lines are shown in red and glide lines in blue.