This Y-Feeder can be placed in front of your bowden input to the cold/hot-end to make it a dual color system. Of course you still need an additional stepper drive.
The design was made in FreeCAD and is fully parametric. You can change the most important parameters in the spreadsheet and the model will be instantly updated. Just export the model to stl for printing afterwards.
115% flowrate for clear PETG (I used DasFilament)
best printed standing so that the filament channel doesn't get blocked by drooping plastic