So, in my study, I've got some twin-slot shelving rails (specifically B&Q's "flexi" system), with shelves on, as normal.

Now, I'd like to mount some stuff (power strips, etc.) in the same plane as the wall, so I'm thinking that I can mount some fibreboard vertically to the upright rails, spanning at least two rails, preferably so that it mounts into the existing slots in the rails.

But, I can't figure out whether this kind of bracket is available, how to search for it, or -- if it's not available -- how to mount something like that myself.

Ideas?