This is a major upgrade to my previous Filament Spool systems. You can still use the same Rubbermaid 21 cup food storage box but will need to add one more hole. This spool system has been gradually developed for 18 months and each part has had several iterations as shown by the version number labels.

This upgrade has several advantages. With the old system the rollers could come off the track if the box was tilted, with the new system the box can even be upside down and everything remains stable. The new system has a way of monitoring the humidity of the filament and the filament is less likely to tangle or come off the wheel.
There is only one large part to print, and this will take about 6-8 hours depending on your printer. All the other parts are small and can printed quicky and will small amounts of leftover filament.

There is a template for drilling holes to mount the base to the Rubbermaid ‘lid’. (Because of the reversed position the ‘lid’ will now be referred to as the ‘base’) Print the template with your 3D printer or your digital printer at 100% scale.
The system consists of a few basic parts and many extras. The basic parts are the base and sides, 2 mounting screws and one spool support. All the other parts are up grades.
All the parts have been printed with PLA 3 layers and 20% infill. Print the parts as presented without support.

After you print the sides and base, slide the sides into the slots in the base. These need to be fixed in position with 1.75 filament as shown in the picture. The sides slightly angle inward by design. The sides are fixed in position with a short piece of 1.75 filament. No glue needed. Next drill 3 holes into the plastic cereal storage box base using the supplied template. Two holes fix the base, and the third hole is for the filament exit. Drill the holes slightly oversize. A tapered drill (shown) is highly recommended.
Print the screws and twist them several times into the base to make sure the fit is smooth and tight. The filament screw is a special design which traps the filament and keeps it from retracting inside the box but also allows the filament to be withdrawn when the screw is removed. Be sure to create a small fishhook bend at the filament end. See pictures b1 to b5.

The spool holder axel holds the spool in place and is designed to work especially well with modern disposable cardboard spools.

PRODUCTS NEEDED:

may be found at a cheaper price at other locations.
Amazon: Rubbermaid Modular Food Storage Container 21 cup size
Amazon: Dry & Dry 10 Gram [40 Packets] Food Grade Silica Gel Packs

You are ready to go! But if you want something extra follow along.
To monitor your humidity, you will need to print the humidity module holder and snap it into place. It mounts to the front post where the filament exits the box. There is also a goose neck filament guide the fits over the front post. This helps guide the filament back onto the spool when pushing the filament back into the box and forces the filament to unwind from the center of the winding. See figure 10.

Amazon: Veanic mini digital temperature humidity meters LCD
These humidity meters work very well, the battery lasts about 8 months and can be easily replaced.

If you do not like the basic axial for the print spool you can print the axial and spool axial wheel shown in picture 9. This will fit spools made by Voxel, Polymaker and most likely many other brands. The wheel was designed by jaimepavlich (Thingiverse 3652656). This is a SCAD file which allows many variations in size. The original design was for ball bearings, but I found this was too smooth and resulted in freewheeling of the filament resulting in tangles, so I made the hub smaller and used a simple shaft.
Finally, if you want to get really fancy the overhead filament guide can be installed. See figures 11 - 14. This will force the drawing of the filament from the backside of the spool. I have found this somewhat helpful with tangled spools but otherwise is of limited value.

Spool Shelves

The Prusa (which I have) and many other 3D printers like to have the filament feed from above. You can mount the spool to the cross bar (which I do not personally like) or build a small box like structure to hold the spools (and my filament system boxes). I am enclosing to design and the Fusion 360 files so you can make your own. One is very simply made with 4 pieces of ½” MDF (fig 15) the other if very fancy (fig 16, 17) and is made with ½ plywood and cut with a CNC machine. I have made both and like the fancy one!
IN GENERAL, this system is not able to dry damp filament, but it will keep filament dry for several months. When the filament is first placed into the box with the desiccant, the humidity will be in the lower 20’s. Within about 2-4 months the humidity will rise to 30’s. At that time the desiccant should be refreshed and replaced.