Same here, we use plastic tubs and tuperware style containers.  Just add
water and freeze.  When ready to cut just lay some paper towel or guaze
on top of the ice and add a little water.  Then face your blocks and
place on the ice.  Ours hold 40 blocks and when you are done facing the
last block, the first one is ready to cut.

Ross Stapf
Histology Supervisor
Washington Adventist Hospital
Takoma Park MD