Now that I have a dual extruder Ultimaker, I revisited my first model uploaded on Thingiverse.I have no idea how people print dual extrusion with other software. But use the _a and _b stl file as you normally would.I'm working on the software for the Ultimaker, as you can see on the photo, there is a "minor" oozing issue to solve. The print also de-attached it self from the bed before it was finished, and the 2nd color didn't come out at the start.I printed it to see if my heads where on the same level, which they are. So I'm very happy about this print.