Yet Another Müsli Filament Dry Box

This is another filament dry box based on re-using a standard müsli/cereal box as enclosure. I made this mainly for learning 3D design purposes and going to share it in case others would be interested.

It is essentially a bottom case taking up rollers with ball bearings for the filament spool, a basket for silica gel desiccant and a hygrometer/thermometer. The top cover is a müsli/cereal container and the gasket of the original container lid is re-used in a bottom case slot to ensure airtight closing along with two cover clips.

A standard 4mm PTFE tube connector is screwed into the bottom part (washer goes into a slit from bottom side) which allows to print directly from the box. When not in use, the PTFE tube can be plugged into a bracket/fixture to still ensure airtight sealing.

To keep the inside dry, we need to add silica gel desiccant into a basket at the rear side of the bottom case. To simplify filling, a mating funnel can be printed optionally.

Printing

All parts were designed to not need any supports for printing. The bottom case has few short bridges (12mm), which print without issues. The two rollers for the filement spool need to be printed vertically and I recommend adding a brim, since the bed surface is small. If bed adhesion is good, no support is needed, but adding snug support to the build plate only can help if struggling with adhesion. The silica gel funnel has to be printed upside down i.e., with the large opening to the build plate.

I printed all in white PLA on a Prusa MK3S+ at 0.2mm SPEED profile. Since most parts have rounded shape, random seam position is good and especially helps the rollers to avoid a continous seam line which can block the rollers due to PLA being crazy smooth with almost zero friction against the spools.

I added a Prusa Slicer project (.m3f) with all needed components on the build plate to print all in one. Also added a gcode file for that, which should print fine on a MK3/S/+, but I would recommend to use the project and apply the setting which works best for anyone.

The all in one print takes about 15 hours (on KM3S+) and consumes about 200g of filament.

Additional Parts

I used the following supplemental parts.

• https://www.amazon.de/dp/B08CKB2B12 
  Müsli/cereal box, 4l
• https://www.amazon.de/gp/product/B08K936Y1Z 
  Ball bearings 608ZZ, 22mm outer diameter, 7mm width, 8mm axis, others with same dimension will be fine as well.
• https://www.amazon.de/dp/B07SKX5P9P 
  4mm PTFE tube connectors/fittings
• https://www.amazon.de/dp/B01DF2SIFI 
  M10 washers for PTFE tube connectors (flat ones, max. 3mm width can fit into the bottom case opening)
• https://www.amazon.de/gp/product/B08ZK8BTNN 
  4mm PTFE tube
• https://www.amazon.de/dp/B0BXRDWYG2 
  Thermometer/hygrometer. I chose this one over the common black rectangular ones since it measures down to 10% humidity (most others do 20%) and uses a solid CR2032 coin cell instead of the tiny LR44 cells. However, the common black ones also fit into the mounting bracket of the bottom case.

Cost

Depending on filament used and pricing of the addtional parts the overall cost of one dry box might be around 12,- EUR.