A 3x3x3 with a hole through the center.
6X6X6 & UP
The first 7x7x7. A seven layered cube.
CUBE (SHAPE CHANGING)
Taking the concept of the Rubik's cube and turning it 45 degrees.
2x2x3 (aka: Slim Tower)
A formerly custom now mass produced 2x2x3 cuboid, commonly known as the "Slim Tower"
Custom made 2x3x3 cuboid, invented by Tony Fisher.
This is a newer version of the Megaminx, published by Meffert, with tiles and 12 distinct colors.
SIAMESE & FUSED