Square Rings

One of the rings was the first pattern I tried to solve. Modifying an existing Delphi program for hexacubes the solution was found in four steps.

Like a woodpecker you can remove each single piece with a mouse click and then put it back again. At the top left corner you can rotate the whole configuratien.

A representation of the solutions using layers is also provided.
What about the 3x 24/18 ring? 16 heptominoes fitting only a 4x4 rectangle must be placed in the corners. Is this pattern possible?

The Real Puzzle
(cut form a beech board 18mm thick)