Working in batches, remove a chunk of modeling chocolate from the tub at a time. Lightly knead if stiff (be sure not to over-knead). Sandwich between two sheets of wax paper and use a rolling pin to roll out. You want it to be pretty thin so it doesn't weight down your cake pops too much. Freeze for 5-10 minutes until stiff (don't skip this step, otherwise modeling chocolate won't cut easily)
Once modeling chocolate is stiff, use a 4" circle cookie cutter to cut out circles (If chocolate starts to get too sticky, return to freezer to stiffen again). Once all of your circles are cut out, return them to the freezer once again to stiffen.
Use a small circle piping tip, or anything with a small tip (like the end of a chopstick) to poke eyes out. They should be slightly lower than center. Return to freezer until just ready to assemble.