I recently bought a shelving unit from the local B&M discount store mainly to use for shoes by the front door. I felt the wall fixing kit included was a little lacking so I came up with this in order to secure it to the wall behind (avoiding the skirting board) to prevent it from tipping over. Once secured it is very sturdy!

This does require 2 M5 heat set inserts (I used Ruthex, but I am sure others will work) and 2 ~25mm M5 bolts, as well as a single 4mm screw to affix the rear piece to the wall. I would suggest printing 2 of these and mounting them as wide as possible near the top of the unit in order to provide the most steady shelving.

Also for reference, the width of the poles being clamped is 14mm, in case anyone wants to use these for some other purpose.

I printed this in PETG but I am sure all the other common filaments would be suitable.

Link to the shelving unit I purchased: https://www.bmstores.co.uk/products/essentials-8-tier-storage-shelf-395740