I'd been using the metal racks that hold 4/8 guns and are vinyl coated but wanted to get a little more storage density out of my safe.

I found these el-cheapo chinesium racks on Amazon and for what they are/their price point, they're exactly what I needed: https://www.amazon.com/dp/B0B1WN5PRR (not a referral link).

You can still see one of the metal racks in use until I find something I like better - the size of the magwells on those don't fit the dividers in the smaller one. Beyond that, 50% more guns per shelf is a nice start.