@bunny_jane I think the idea with the painter's masking tape is that the blue stuff doesn't adhere as much to the plate so it can be peeled off when it's served its purpose without leaving sticky residue on the build plate, especially after the heat of the PLA filament, but also the top absolutely will not let any filament through and won't burn on contact with hot filament? Idk, i've done very little extrusion 3d printing, but the blue masking tape DOES feel different to regular masking tape.