Doh! The belt purge thing is only visible in the live stream of the same print. It is much less satisfying of a video but you can see the MMU in the background switching filaments and and a small wheel below where the extruder parks:
[URL unfurl="true"]https://youtube.com/clip/Ugkx39EKaGnkDdPcycQbnvj3y0V4CuWysB7G[/URL]
Blender can be used for 3d printing models but if you use a model not specifically designed for printing you do want to run it through netfabb or meshmixer or just prusaslicer (which has netfabb built in) and have it fix any holes or gaps. Blender can export Stl files though so if you ever want try organic modeling its clay sculpting tools can make it really easy to achieve soft round shapes that would be nearly impossible to do in CAD with significant complexity.
I am not sure what model they started with but they seem to be using blender to separate out the different colored parts into distinct models which is the cleanest way to do multi-material prints. They are going around and patching holes and fixing the model to be manifold manually and their slicer probably takes care of anything small they might have missed. Alternatively they could use Microsoft 3d builder or other software to paint the model into different colors which is probably slightly less tedius but might not make as nice of a timelapse video since youll see the insides and expose its “painted” color changes.
