The Ultimate Spool Holder (TUSH, https://www.thingiverse.com/thing:2047554) was one of the fist things I printed, and in fact the TUSH works pretty well, and using the cheap bearings is a great idea.

However, when I bought a new box for more filament (Google: 508549 Clip & Close 10,6l), I found that the spool on the TUSH was sightly too high and did not fit into the box. The inner height of the box is something between 200 and 204 mm (both the bottom of the box and lid are flexible), Since the diameter of a spool is something between 198 and 200mm, the spool holder must not add more than 2mm to the diameter of the spool.

There is another negative point on the TUSH design: Using the TUSH in a box is a wiggly adventure, and when changing the spools or moving the box, the TUSH very often slided away or fell aside.

So I made my own design with the following targets: a) the spool holder must have a minimal height underneath the spool, b) the spool holder should be adustable to various spool sizes and c) the spool holder should not be slippy and wiggly in the box.

The thing in this design is the result: Each spool is placed on two spool holder elements that are slotted on two racks (rulers). Each spool holder element has two bearings (608) which are located so that the spool has a minimum gap to the bottom. Silicone bumpers (d = 6-8 mm, h = 2 mm) under the rulers and under the spool holder elements provide a 2mm gap to the bottom of the box and prevent the spool holders from slipping around in the box. The length of the rulers (169 mm) is optimized to fit 3 x 750g spools into one box (but it's also more than wide enough for 2 x 1kg).

I checked the box "Customizer" because it's true that you can change some design parameters, but I cannot guarantee for the results. When changing the parameters, please thoroughly check the results. It's best to use the design "as is".

(The Filament Box Grommets are this thing: https://www.thingiverse.com/thing:2838281)

12.06.21 Update: I made separate .stl files for the rulers and for the spool holder sides. The design is unchanged.