Slightly overengineered slim, side mounted filament spool holder with simple bearings for P1P, P1S and X1C.

There are five 3D printed parts needed:

1x main bracket
1x spool roll
1x bearing spacer
1x inner end cap
1x outer end cap

Used printing parameters

PLA
0.6mm nozzle
0.2mm layer height
4 wall and top/bottom layers
50% infill

Most other needed parts are fairly standard

1x 185mm aluminium tube, 8x1mm length, i.e. 8mm OD, 6mm ID
2x bearings type 608 8x22x7mm
2x M3x20mm button head screws with washers
1x 6mm plastic dowel
1x 3,5x35mm self-tapping screw

Additional modifications

Replace the standard 550mm PTFE filament tube by one with 800m length
Add a second tube fitting to the outer end of the rubbery tube duct

I'd be glad to receive some feedback or comments for further improvements.

The shown setup is currently undergoing testing on my Bambu Lab P1S.

Update:

Added STL files for holding 2kg spools with extra 50mm width.
This is untested so far, please try at your own risk.
Just print 1x wide roll and 2x wide bearing spacer and use a 235mm aluminium tube.

Why this design?

I don't like the original Bambu Lab metal holder - 
so I didn't like the designs re-using it either
I liked spool holders with bearings from my earlier printers as I found them 
to be more reliable, especially with slightly tangled filament
The bearing-based designs I found for download are comparably bulky