Ninjatek makes great flexible filament. Unfortunately when they released 1kg spool they re-used same spools meant for 500g filament. It's too small for that so filament falls off and tangles during the print. It also prevents spool from standing on rolling type of spool mounts.

I discuss this in my "Made in Basement" Youtube Series: https://youtu.be/na1naeLyRdI

I designed and laser cut larger rims for the spool To hold them together I also made 3D printed hubs.
Hubs attached to rims with m3 screws and some nylock nuts.
M8 or 5/16 bolt holds both sides together (you can also use threaded rod).
If you don't have access to laser cutter, you can print rims as well.

Creality

CR-10

No

No

0.3

15

Hub is very easy to print at any settings. No supports needed, just flip STL file the other way (larger surface down).
I didn't print rims (they were laser cut) but you can probably use fastest settings for these as well.