When I didn’t know when I would receive my GF, I ordered a similar product on Amazon, but it turned out to be cheap foam/gatorboard, which meant it wasn’t that secure. It held my phone horizontally pretty well but was juuuuussssst too wide to hold my phone up vertically so it kept falling over.
I finally got around to redrafting a more narrow version of this to fit my phone in both directions, and it seems to have worked out swimmingly so far! This is made from medium PG draftboard.
