1.75mm filament colorizer

I tried out the other filament colorizer, but got very inconsistent results due to what I think was smaller-than-designed filament size. So I designed this one specifically to fit 1.75mm filament, as well as to be much more minimal - it prints in < 20 minutes and takes very little plastic.

All things considered, this works, but it has a lot of room to improve. I'd like to add some way to clip connect it to the extruder head firmly (perhaps by modifying the Mk7 filament drive block?), and I'd