These coins are almost exactly the same size as the original paper ones. They consist of 2 parts, a disk and the shell. The shell has a “heads” side and a “tails” side.

You should print the disks first, and you might want to print small batches in different colors. The shells will pause printing when they're ready to have the disks inserted. While you're inserting the disks, you'll probably want to turn the fans down low, so the disks don't blow around. After you insert the disks, restart the print, and keep an eye on it until the printer gets another layer down to secure the disks in place. You might have to pause and re-insert a few.