After many, many revisions, I have a phone case I like and use regularly for my Pixel 2 XL. I built this with the help of Laen's P2XL model as a starting point. I found that that model (or the version I have of it) was a bit off and missing at least one part, but it was very close and have corrected it enough for my purposes. I suspect it's still not quite perfect.
The main feature of this case is that it includes a wallet on the back. It slides in as a separate piece, which I then glue on. This is the reason I had so many attempts. I wanted a wallet that would work for the cards I keep with me. Things like library card and insurance card are not exactly the same dimension as other cards, so this is somewhat challenging. However, it fits the 7 cards I keep with me at all times pretty well.
The other major challenge is that I wanted a case that would hold my Yubikey snuggly. I tried several variations and the one I finished on here works pretty well for me.