Over the holidays I dropped my phone into the snow. Again. After cursing some, thinking some, and then cursing some more, I decided to make a backing for my phone that was less slippery than the glass or even the metal one I have. I went through a few materials (thin adhesive-backed silicone, adhesive sandpaper, and some others) when I arrived at the perfect solution that takes care of everything all at once: skateboard grip tape!
iPhone grip tape backing