Code used: Hairizer 1.2 By Magonegro (04-NOV-2020) from thingiverse. The code was used to generate the bristles.

This file isn't perfect, but it is usable.   I have uploaded some minor improvements, definitely more to do. Updated this file for the related contest.

NOTES:

-As you can see from the photos, if the bearing from your original brush still works, you can use it. I've tested it without the bearing and it still works.  

-I recommend printing small test slices of this file like in photo 3 to dial in what settings your printer needs, rather than printing out a bunch of failures (like I did)

-The bridges must be done slowly.   Didn't work with default settings on an MK4, worked with custom settings on a MK3.  Have now got it working on a mk4 with settings tweaks

-Some settings that helped: External perimeters first, manual grid supports only on the bottom disk, “Perimeter Generator: Classic”, Seam position randomized, "Automatic extrusion widths calculation

-Haven't tested different layer heights, but I did mine at 0.2. You probably need to edit the scad file if you want to do 0.1 or 0.3 

-I did this in PLA. I recommend you do it in PLA. God knows how much microplastics this will generate, and I'm only really comfortable breathing/ingesting PLA.

TODO:

-(DONE!) I'll be tweaking the measurements to make the bristles line up with the string-rails

-try and figure out a mod where I can use a more standardized bearing

-(DONE!) I'll  comment  the code eventually…

-Add recycling symbol somewhere