Filament painter
thingiverse
Add any dye after feeding your white filament through and it will automatically change the color of your filament once printing starts. For Ender 3
Download Model from thingiverse
With this file you will be able to print Filament painter with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Filament painter.