This is the single file version with much of the landscape cut off to maximize the castle build area to make it more multi color filament friendly. Its a remix of Medieval Castle here. https://www.thingiverse.com/thing:862724 The Rainbow PLA I used I got here: https://www.amazon.com/gp/product/B01IBF2T0Y/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1 And the rolls come with random starting colors. I got lucky and mine started with green. There are 4 colors per roll with each of the same color repeating once. That means there is about 12% of a solid color (or 120 grams) (leaving 1% as the transition color) before a color change. Using that info and adjusting your infill on the model to use the right amount, you should be able to create the color change you want at the right time with some degree of accuracy.