I've been using these inexpensive garage shelves for organising components and kit in my workshop. They're great for what they cost and hold a lot of weight. They come in various widths, depths and height, but they're all based on this kind of design...
180cm x 90cm x 45cm, Black 5 Tier (175KG Per Shelf) Garage Storage Shelving Units
I wanted to be able to hang up a small trash bag from the shelves, as they're close to where I have a couple of my printers and soldering station.
I didn't want to put a bin down on the floor when the shelf has perfectly suitable vertical supports. So, I came up with this in Fusion 360 in about 5 minutes, sliced it in Cura with 15% infill and then left it to print on the Snapmaker. You'll want to orient it on its side when you print for max strength.
It just attaches to the shelf unit with cable ties. I wouldn't hang anything super heavy from it, though. I haven't tested exactly how much it can hold, but chances are, the cable ties used to hang it to the shelves would stretch and break before the bracket does.
I printed this in PLA, because it was what was loaded into the printer at the time, but you could also print it from PETG or ABS. I don't suppose it matters much what you print it with, really, as you're probably not going to be holding big weights with this.
I've included a couple of gcode files for the Snapmaker. One is for a single bracket, one is for four of them arranged on the bed so that they all fit (Cura couldn't figure it out by itself). The single bracket should print in about an hour.
Generic PLA Generic PLA