Except for my original PS1 and Megadrive consoles .... I'm pretty much a 2600, cart only acquirer .. coz I like to play Hence I have a mild mannered Clark Kent collection that's pretty easy to maintain. Regardless, I'll use these .. https://www.retroprotection.com/Atari-Box-Protectors_c40.htm.. for clean level stacking of carts and simple Ikea cube shelving. I take a leaf outta McGiver's book and cut down some local cardboard fruit boxes to narrow the depth of the shelves, moving the carts more forward for better accessibility. They're hidden so you would never know. You can pull a cart anywhere from the stack without issues. These Ikea cubes hold EXACTLY 4 carts wide. Atari foresight in mind?
My controllers are inside large zip lock bags, inside plastic bins next to the TV cabinet. You'd be surprised how many they fit. The boxes in the pic have PS1 and Sega controllers, Atari paddles x4, x2 Driving Controllers, x1 Keyboard controller and cx40s.