Not the best, but simple solution.
Just print whatever you want. Put on the spool and filament sensor. And that's all. Can be used. Of course, if you have a 4mm PTFE tube.
I use a tube id = 3mm od = 4mm. (Works great. Pulls out without any effort.) Haven't tried to use with tubes of a smaller inner diameter, I think there may be problems due to too long path.
Use mirroring for other side.
The author marked this model as their own original creation.