Can you help identify these clips (or a replacement)?

I’m trying to repair an old but nice computer desk that I was given. It was made by Danish furniture company B8 Mobler about 35 years ago, with a wooden sliding keyboard tray attached to the metal frame by 4 clips. Unfortunately careless movers broke all the clips:

The broken-off part (above left) is supposed to go around the frame:

Assembled, the clip would have a C profile and be about 40 x 25 x 10mm, with a slot about 15mm deep by 5mm wide down one long side. (The bottom plate is separate, but fits into the "upper" corner clip which is snapped in half).

I have contacted B8 Mobler but I doubt they are interested or still have any stock of the original clips. I’m looking for a replacement, but I don’t know what they are called. There are no useful markings that I can find on the clips themselves. They don’t need to be identical, just to screw onto the wooden tray and slide over the frame. The slot can’t be too wide because it needs to press against the frame when a screw is tightened, holding the tray firm.

Something like T Clips for decking might work, but they look too thick, and come in large packs which is wasteful? Beam clips might work, but they all seem to be metal and would scratch the metal frame. A flange clamp would probably work, but they’re also metal and seem to fix with a bolt, not a screw.

So I can probably find a way to bodge it, but what would be the nicest/cleanest way to fix it? Can you tell me what these clips are called, or something similar/compatible?