IKEA Vidga slider for Aqara

The beloved spouse asked for some motorized curtains.
As we live in IKEA-country, we have the IKEA Vidga curtain rails already in a few rooms.
The simple solution was to get a few of Aqara's Curtain Driver E1's

However, the IKEA Vidga curtain rails now only comes with some simple plastic sliders.
For normal curtains, I'm sure the sliders are just fine, but the Aqara motor pulls itself hard onto the track to get enough friction for its drive wheel.
Hanging the motors in the sliders wasn't a solution I would trust to last long and without issues. 

IKEA used to have some wheeled rollers and It's possible to find them from various sources, but they were surprisingly painful and expensive to source.
Besides, I only wanted 2 for each motor - not for the entire curtain.

So I took inspiration from Juanfra's Ikea Vidga compatible linear rail, whom suggest using 623-ZZ ball bearings (ID: 3mm, OD: 10mm, W:4mm) 

I sourced some 3mm stainless steel metal rods and the ball bearings from Amazon.
Using a Dremel with a cutting disc, I cut 8 x 12mm pieces of the stainless rods to use them as axles.
I gave each end of the axles a slight round over and polish, before press-fitting them into a simple body designed in FreeCAD and printed in PETG.

Onto each axle, two ball bearings are installed and the entire thing is installed into the track that also keeps everything in place. The ball bearings slide easily onto the axles - no press fitting or anything.

All in all, it turned out surprisingly well.
There is enough room to make everything slide easily and I have been unable to make them NOT run smoothly in the rail.

It's been a hot minute since I used FreeCAD and the model could probably have been made better by a 6yo kid - but it got the job done and it's easy to change it.