it’s not super complicated…. Below the box you type comments in there’s a button that says upload a file. Click that and you’re off to the races.
There are four ways (outside of the mint) to make a double-headed coin. Least likely is to create dies and strike it that way Make moulds and cast a double-headed coin - leaves an sprue mark on the edge You can remove the reverse from two coins with some abrasive device - this method leaves an edge seam. or a lathe: (The first 5m of that video focus on making the tool to make the double-headed coin) You can use a lathe to remove the reverse and a tiny bit of the rim on one coin, then use a lathe to create a matching pocket on the second coin.