The Patina wall is a building-block with a pale red pumice-like surface framed with a green patina-colored frame on 2 sides and green patina-colored metal-like surface with 2 metal straps on 4 sides. It can be crafted in your Crafting Menu (default key "Q") or at Crafting Tables (that still exist in worlds created before R22 on September 16th 2015), after the crafting-recipe has been unlocked upon taking/crafting Ruddy Stucco Wall for the first time, which is unlocked by Stucco Wall made by Canyonstone. To craft 8 (blocks of) Patina walls at a time, you'll need (as of R29 in February 2016):