As with the edge-connected one-sided pieces we get 18 different shapes here, too,
and we can look for some "convex" polygons with straight, jagged or mixed edges.
Together with the set of the 18 onesided edge-connected pieces we have 36
pieces and can try to construct models 6 times as large. This is possible
for all 12 simple pentominoes and for some pseudo pieces. Can we get a replica
of a piece with three corner connections?