Caliper holder for metal garage shelves

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](https://amzn.to/2YVLcoC)

In an attempt to get more organised, I've been using the free spaces in the vertical supports to make attachments for various thing