You dont need a multicolor printer .

Use M0 on the layer to change color (prusa slicer )or pause at height (cura ),

Open manually your extrudeur and change the filament . ( press the key ).

Or you can use paint ; first use mat varnish, then use paint like vallejo , citadel ,etc.. and satin or mat varnish .

Be sure to have your layer 0.2 first layer 0,2

For the heart change color :

layers 1 to 20 : wood

layers 21 to 23 : red

layers 24 to 27 : white

28 to end : black

For the base :

if you use prusa slicer 2.6 beta or cura, its better to use organic (tree) supports.

my others design

https://makerworld.com/en/u/2044748376

enjoy !