The method he uses is as follows:
- Create a multi-color object as different STL files (the different colors being only 2 layers thick [he used layer height of 0.1mm]).
- Using the "Align selected model origins" (under the Edit menu), he correctly place them in their locations.
- Now comes the tedious part where he selects each part separately and slice only that one part (for 2 layers). Saving them in sequence.
- Finally he prints them out 1 part at a time, without removing the previous prints from the surface.
I propose a little bit of more automation in this process:
Being able to group objects into color and material groups (this way S3D determines the most efficient way to print these objects; for example all the 'white' objects first, up to 2 layers high; then all the other colors/materials for the first 2 layers). Next it goes into the next set of 2 layers, trying to continue off with the last color used for the previous 2 layers to speed things up. This repeats for the whole object. S3D add the M600 command (along with temperature changes as required by the different processes selected for each color/material group) at the right places.
Finally S3D also generates a note on the sequence the colors/materials will be requested (since someone will need to do this manually).
While I agree that this multi-color/material is not practical for creating the same objects as can be made with multi-head printers (simply due to the number of filament changes being so high), being able to do this for a few layers typically will be awesome.
I have used this technique now for a few weeks, combining PETG and Flexible filament to create phone cases (different colors are in PETG). My latest one, have 7 filament changes total (excluding the change for the 1st color), with all colors and materials used on layers 1-4, then an internal white backing on layer 5-6 (internal is not visible from outside, as it is surrounded by the flexible) and then continues with flexible to the top. I can share this file, if anyone is interested in how it works and looks inside of S3D, after manually assembling it (made for a Wanhao Di3, with a Flexion Extruder, running the Repetier V1.0dev).
Currently this process takes me more than an hour of extra preparation, which would be nice if we can have it reduced.