Czesc :) We like these ideas. Do you think you can change #89 to be just one triangle? (So it will look like more like impossible triangle). We also very much this idea:
http://2.bp.blogspot.com/_qC54jayKgko/SMu8l1j57sI/AAAAAAAABhc/YIx-ZIGLN2I/s400/impossible-triangle.jpgEspecially with the separate blocks and the fact than one block is outside of the triangle.