Sunlu Filadryer S4 spool rollers

Similar to another user on here, my Sunlu S4 dryer was missing all of the filament rollers when it arrived. I didn't feel like dealing with Amazon or Sunlu's crappy customer service, so I came up with my own solution.

This design uses a hybrid design of off-the-shelf components and printed components to function.

Purchased parts:
Bearings are a 604ZZ with double shield from Amazon. 4mm (ID) X 12mm (OD) X 4mm (Thick). I bought a 20 pack to cover demand + spares for my random bearing inventory. Price is $13 for the 20 pack.
uxcell 604ZZ Deep Groove Ball Bearing Double Shield 604-2Z 80014, 4mm x 12mm x 4mm High Carbon Steel Z1 Bearings (Pack of 20): Amazon.com: Industrial & Scientific

Axle shaft/carbon fiber rod is a 4mm diameter also from Amazon. I bought the 10 pack of 200mm long shafts to use on other projects as well. Price is $12.99 for the pack of 10. Note that these get cut down so a 200mm shaft is enough for 2 rollers - you could get away buying the 5 pack instead and save a full dollar!
Amazon.com: ARRIS 4.0MM Carbon Fiber Rod 200mm Length for RC Airplane DIY Craft 1mm 1.5mm 2mm 2.5mm 3mm 4mm 5mm 6mm 7mm 8mm 9mm 10mm Matte Pole 7.87inch 5PCS : Industrial & Scientific
These shafts need to get cut down to 86mm as shown in the pictures. I used a cutoff wheel in my grinder and finished it off with a bench grinder. You may be able to get away with a hacksaw or something if you don't have as much of a shop.

Printed parts:
There are 3 parts (qty 2 and qty 1) that you need to print for this design. Quantity 2 “Filament Dryer Long” and qty 1 “Filament Dryer Short”. This is enough for one roller so be prepared to print a few if you need to make enough rollers for a complete S4 that uses 8 rollers.

For these printed parts I used Polymaker's PolyMide CoPA nylon filament. I really, really like this filament and highly recommend it. Uses a PA6 and PA6.6 blend to provide performance and make it easier to print.
PolyMide™ CoPA – Polymaker US

Note that a high heat resistance filament is recommended. I have no idea how PETG or PLA would act in the environment of the FilaDryer S4. I'd imagine that it would not fair well. I recommend ABS/ASA at a minimum.

Note that I colored in the short pieces with a sharpie while fiddling on a boring conference call. No need to print a second color if you don't want to.

Design:
Instead of one really long cylinder/sleeve I broke it up into two variants with the anticipation that one (the short one) would need to have the height adjusted to fit the dryer properly. Ended up working just fine on the spacing so the printed parts didn't need to be modified. However, I did have to print a couple iterations to get the inner Ø to fit over the carbon fiber rod properly.

Note that the diameter of these carbon fiber rods must not be held to a super tight tolerance. You might need to sand down the ends to fit the bearings properly. Be careful when cutting and sanding the CF as it is not something you want in your eyes or lungs.

Conclusion:
STL, STEP, and IPT files are included. Feel free to remix, post a make, or leave a comment on how dumb this design is.. - hoping this upload can save someone a couple minutes and get their dryer working as it did mine.

-Jonathan