Cubed consists of 6 pieces that form a 5x5x5 cube. Cubed 8 has 8 pieces to form a 6x6x6 cube.
The assembled puzzle has a side of 3.6cm. The pieces don't align very precisely on the exterior, so it doesn't look as elegant as it could.
The difficulty is much higher than Cubed. It takes a total of 35 moves to take out the first piece, and an amazing 21 moves just to get here:
The puzzle works fine; it was a bit tight initially, but the excess material came out after rubbing the pieces against each other a few times.
I made the pieces hollow to save on material, using 0.7mm walls, but I think that this way the pieces are a bit too flexible which gives the puzzle sort of a rubbery feel. Here are all the pieces after disassembly: