Slide the tabs over the monitor panel and this tool holder matches right up; same height and angle. All tools that come with the Ender 3 fit. Sturdy, material-conscious build (77 grams); 1.5mm walls and anything else was trimmed out. Having the holder kept on the side, lining up with the monitor panel, makes it look like it's part of the unit and leaves it accessible while being out of the way.
Pliers are housed in the back, USB stick/fixed wrenches/screwdriver/chisel/allen wrenches are kept on the side.
Added 1mm to the overall height, as I was noticing it was just shy of sitting flush with the panel.
In regards to StrahdVonChairovich's comment, I have widened the clipper slot to 16mm (+3mm), created individual slots for the hex keys, and changed the arm to be two 10mm wide tabs that are 1.65mm apart (the thickness of the panel). This should give ample room for the clippers, keep the keys looking orderly, and make certain their aren't issues keeping the holder in place.