This is a wrench to tighten/loosen the T-Handles Hex Allen Key (https://www.printables.com/model/70527-ufs-094-t-handles-hex-allen-key-wrench, https://www.thingiverse.com/thing:4716243).

I designed after I had to take my Allen keys in and out of the T-handle several times while working on a project.

Also available on Printables: https://www.printables.com/model/418887-t-handle-wrench