One thing I really like about Borderlands 3 is that you get your own room on Sanctuary to decorate however you see fit. It's a good idea and I can't tell you how many times I've wanted other loot-based co-op games to give you some space to build your own.
Where to find your room
Your room is located at Sanctuary Reading, right next to the fast travel point and the Lost Loot Machine.
How to decorate your bedroom
There are a few empty hooks on the wall that will allow you to place decorations if you approach them and press the interact button. There are three hooks in total, but one of the spotlights is quite dark, you might want to put a neon sign there. There is also a row of panels on one of the walls that will allow you to place a weapon or equipment. It's really nice as the weapon hangs on the wall, and the exterior of the panel will glow with the rarity of the weapon's colors. It's a very cool way to show off your awesome legendary and epic weapons.
How to get decorations
While any weapon can be placed on the panels, you can get wall decorations by opening chests, completing missions, and purchasing them from Crazy Earl. You might be better off saving the Eridium for weapons and the like, and letting cosmetics be your own personal goal when you already have a ton of cool weapons, but it's your choice.
And there you have it, everything you need to know about your room and its decoration.
