The start of a 3D printing filament mini factory. Note: You need 2 semi-compatible filaments. PLA and PEI or PEEK don't work together due to the temperature differences, but PEEK and PEI should work given your hotend can handle it. A great example for a good material is PLA and PETG. However, beware that PLA and PETG don't stick well to each other.

Print instructions

Get 2 filament spools ready. The printer will pause mid print, or whenever you specify. Use that pause to switch filament. IF YOU WANT MULTI COLOR OR FILAMENT FILAMENT, THEN YOU NEED THE PAUSES, OR MODIFY IT FOR MMU.