Get a block of wood and drill holes in it to the depth you want/need.
One of the advantages of this method is you get to make the holes far enough apart that clumsy fingers like mine can actually pick up a cartridge from anywhere in the block instead of just along an edge.
Also, Why in the heck do the RCBS loading blocks hold 80 cartridges, but most plastic boxes to store the ammo in comes with 100 holes? Seems it is like hot dogs, ten to a pack and eight buns