This is a dry box filament feeding system of my own design. The only thing you need to have is some kind of plastic storage box, some kind of sealant for the lid (if it isn't airtight already) and a rod (aluminum, plastic, metal tubing) of max 24 mm diameter (if you don't scale the model up).
The idea was to be free of having to use any metal screws and nuts, so you don't have to deal with precisely drilling the holes for them.
I used a double setup, because the KIS box is large enough, but one can use as many racks as they want.
For one rack you will need to print two holders, two holder nuts and as many feeders and feeder nuts as the number of filament spools you will have on the rack.
The feeders are M8, so they need an 8mm hole in the box to be set in. The feeding hole is 2.5 mm, enough clearance for 1.75 mm filament. If you feel there is not enough clearance, drill through with a 3 mm drill,.
The holders are M24, so they will need a 24 mm hole in the box to be set in. Screw them in tight.
I have designed the holders to have a 3 degree downward angle, because the walls of the box are sloped 93 degrees (see photos).
The clips are specific to the plastic box I have used so if you don't have the exact same box, it is doubtfull that it will work for you. Included in the .rar file are SolidWorks files (.sldprt) for your modification and remixes.
Print in PETG (or PLA - only use indoors, away from light):
-the feeders and the feeder nuts with 0.15 mm layer height and 30% infill
-the holders and the holder nuts with 0.2 mm layer height and 20 % infill
-the clips with 0.3 mm layer height and 100% infill
Print all the nuts without support.
Print the holder and the feeder with their axis vertically (perpendicular to the table). Print only the holder with support (where the holding part is, not where the screw is, that has to face up and print clean).