Kind of a long process. I made one of these a while back and aside from a few problems with my old worn out print bed, everything worked great.
A few months later, I decided to make these for a family reunion. I wanted to put text on it along with a hole for a necklace or lanyard or anything like that, so I actually redesigned the whole thing. I opened the .STL in solidworks and simply remade it based on what I saw there and the measurements I got from the one I already printed. It took a couple revisions but I got a functional design and duplicated it so that it made me 6 at a time and printed out 30 or so. Overall, very happy with the design and I am very glad that someone else already made one.