A desiccant container designed to fit inside spool holes, featuring a fast print time and minimal plastic usage. Some assembly is required.

I looked up existent alternatives and although some designs looked really good, I found that they consumed a lot of plastic or required several hours to print. Printing the grid that allows the air to make contact with the desiccant beads seems to make the process slow (and hairy!), due to the number of hops and retractions required. To address this, I devised a grid that could be printed flat and then bent into the shape of a cylinder. The grid pattern is achieved by abusing the slicer settings (this idea is not originally mine).

Print orientation should be correct from the provided STL (50mm diameter and 65 mm length). If you are exporting from the FreeCAD source then the cap should be rotated 180° around the x-axis. Select the grid and apply the following per object settings. You can also add a cylindrical modifier with the same settings to the bottom part if a grid is desired there too:

• top and bottom shell layers: 0
• sparse infill density: 35 % (this produces 2 mm x 2 mm squares; YMMV)
• sparse infill pattern: grid

I used PLA for its manageable softening temperature, other plastics may also work. For the assembly, read the following instructions and see the attached pics:

• submerge the grid in hot tap water for approximately one minute;
• carefully bend it into a circular shape and clamp it in place to cool (use gloves and tongs to avoid burns);
• let it dry;
• perform a dry fit of the parts to check the tolerances;
• if the grid is too long to fit in the groove, simply trim a small rectangle from the each corner that will rest inside of the container;
• remove the bottom piece while keeping the grid clamped, apply glue and put it back;
• do the same with the top (no clamping this time);
• (optional) you may apply some glue to at the point where the grid overlaps itself;
• fill with your favorite brand of desiccant and screw the cap in place.

Some effort went into making the part fully parametric. I have only printed the attached STL file and a slightly thinner version, both of which worked well for me. Adjusting the length or diameter inside FreeCAD seems to yield consistent results (with the occasional, easily fixed issue regarding failed fillets).