Now, back on topic, my file rack solution is that:
(1) I have a set of masonite trays where my files are stored. The trays are set-up such that they key into one another and each tray is limited to one type of file. Each tray consists of slots such that each file "lives" in a specific (totally surrounded by masonite) slot. A 32 inch wide X 4 inch deep roll-away tool chest drawer holds approximately 300 files this way and is reasonably easy to sort through when looking of a specific file.
(2) Many (many) years ago, I purchased a large set of (hickory) file handles. I hot fit files for specific sizes of file tang; split them lengthwise; and installed pieces of (axially) threaded spacers that were mated to cheese-head screw holes. Thus, when I want a specific file, I have a handle for it ready to hand that only takes a few turns of a screwdriver to make into a tight fit!
(3) I then took pieces of 2X2 (inch) fir timbers and slotted or drilled them for sizes of files. Those, in turn, were glued to a baseplate such that I can lay them on a bench surface, install appropriate files, and not have them tip over as I pull files from the slots or holes. This means that I can set-up an assortment of files for whatever task and have them visibly ready and within reach! These stands "live" on a shelf in another (homemade) roll-away cabinet.
I served my apprenticeship as a tool & die machinist back in the day when filing was still an appreciated skill.