A Bloons TD6 BFB model!  This can be printed in either 2 color, or 3 color.

The model is designed specifically to guarantee there is never more than 2 colors at a layer - thus avoiding wasteful purging.  With an H2D this is best printed with the bright-red filament on the left nozzle, and the white & dark-red filament on the right nozzle.  In an X1C there will be some loss due to purging.