The OttoBox tool holder is a great kit and holds almost all the items I regularly use with my printers. The main item that didn't fit was a notebook that I use to record setting changes, measurements of potential designs, and anything else related to using the printers. The notebook fit well on the rear corners pieces and held itself up, but I wanted something that would support it independently of having any steel sheets in place and that wouldn't let the metal spiral binding rub on the places if they were installed. I used PrusaSlicer to add braces to the rear rail to hold a notepad or a single subject notebook without it touching the spring steel sheets.
I have oriented the file for printing, though I'm not fond of printing the braces vertically. In the future, I may try to separate the rail from the brace and join them with a dovetail joint as used elsewhere on the OttoBox, allowing the brace to be printed flat on the bed. I printed with default settings of two shells and 15% infill using Overture PLA Pro Digital Blue filament.
The author remixed this model.