Just painted the awesome model Reddadsteve made in PrusaSlicer using the MMU paint feature. Hopefully this can save others some time. Please note that the print requires that you change the Brown (log) filament to Red before it gets to Calvin's T-Shirt, then change the Red filament to Yellow before it gets to Calvin's hair. Not sure if the 3mf captures this so you will need to double-check it.
The author remixed this model.