I wanted some air tight containers to protect filament sensitive to humidity (I live in the US NE and some of my printers are in the garage).
I was not satisfied with the options I could find due to specific container limitations, etc.
The container these were designed to fit is a Rubbermaid 21 cup container (part# 1776473). I also modified the containers to feed filament in two directions and added a hygrometer.
The desiccant container includes space in the lid for a magnet (specifically these 32x3mm). Depending on spool size sometimes it is easier to locate the box with an external magnet to avoid interference with spool.
I had to create two different heights to account for different spool designs. The center spool is designed to be used with 8 mm x 22 mm x 7 mm (608RS) bearings. They should just press fit on the end of the two pieces, which I glue together but this is optional. If you have some elephants foot then you may have to sand/shave down the protruding material for a smooth action on from the spool.