You can also just use a beer cooler with the top open. It makes it easier if you learn the timing such that it freezes to just about the depth you want to cut

You can also just use a beer cooler with the top open. It makes it easier if you learn the timing such that it freezes to just about the depth you want to cut the blocks at (about 2") and the rest of the water is still liquid. Then the ice comes out already at melting point and cuts more easily.