Fairly easy to use once you get the concrete recipe correct, it's a shame the seller doesn't offer any instructions. Otherwise I would rate it a 5 star. Only gave them 4 for this reason. My tip would be not to throw out any broken bits as you can use them on the edges. I also use mica powder on the mould first to be able to turn the concrete out more easily as the mould is solid plastic. A silicon mould would be impossible to move with spilling the contents.