Keep your filament Dry while printing.

We all know how important it is to keep our filament dry but it's a pain taking it in and out of the ziplock bag. What's more, while you're printing, your filament is exposed to the air. Nylon and PVA can start deteriorating within hours of exposure.

These rollers are designed to fit perfectly into an IKEA box (Samla 39x28x28 #798.508.75). With a bit of weather stripping and lid clips you can print directly from your dry box.

This 3-spool version uses the tubes and bearings that come with the Prusa MMU2 kit and has space for two 100mm wide reels (same as MMU2 rollers) and one 86mm (wide enough for Prusament 70mm reels).

There are two options for the dry box screws; the Festo Screw and the PTFE screw. The former has threads for screwing in a Festo connector and the later is just a 3mm hole that you can push a piece of PTFE tubing through.

For a 4-spool version (all wide enough for 70mm Prusament spools) see https://www.prusaprinters.org/prints/8018-ikea-dry-box-rollers-4-spools-of-prusament

You'll need to print two copies each of the frame and connector. Plus, three of either the Festo Screws or PTFE screws (PTFE pass through) and three nuts.

You'll need to buy:

• IKEA box (SAMLA 39x28x28mm #798.508.75).
  -2x IKEA SAMLA 4-pack Clip lock (#801.208.43). Cut 2 of these in half so they can be used on the ends of the box - the tighter the better.
  -Some weather stripping (foam or rubber, not brush).
  -Colour indicating silica desiccant.
  -Hydrometer (optional but only £1.50 on eBay)

If you don't want to use the parts that came with your Prusa MMU2 (or you're just using this dry box for convenient ready-to-use filament storage) you'll also need:

• 12x 608 bearings (8x22x7).
• 3x 120mm x 8mm axle tubes (or just print them).
• 3x Festo couplers (there are cheaper makes but be sure they don't have sharp interior edges that scrape the filament).
• Some PTFE tubing or just cut a few cm off the long ones that came with the MMU

Note: I have tried attaching the PTFE tubes from the MMU directly to the box allowing the retraction to push back into the box. It worked but I can't promise the filament flopping around in their won't catch on something. I just let the retacted filament lie on the desk.

Just for completeness I’ve included a couple of O-rings I used for the hydrometer.

I've uploaded my Fusion 360 design so you can edit it. I'm self-taught so only constructive criticism please. :-)