Sean Stall's cube that puts itself together for v8.4 (added 01.22.2008)
Create a 3D DVE node in an effects tree. Load this preset from the property page of that node. Press A to add inputs to the 3D node. Feed each input with numbers 1 through 6 of the dice sides you've created. Select a side within the 3D DVE and change the input to fill that side.