Hey guys,
I've got my printer and firmware all set up for dual extrusion but I don't get how the slicers handle multi-material models. I was able to roughly print an ABS test piece having PLA support with Kisslicer but I don't see how to assign extruders to different shells. Any advie would be appreciated!
Thanks!
joe

I have yet to try this, but I do know that you need to have 2 different STL files to start with.  The slicing program should have a feature to merge the two files together into one G code that designates which STL file goes with which extruder. 

You can see an example of two different files in this model of Earth at thingiverse: http://www.thingiverse.com/thing:11660

Thanks Nate. Yeah, Slic3r  handled the merge ok except for an offset of one of the shells in the Z due to the base on one of the models. I guess I'd need to maybe flip them about the y axis 180 in freecad, merge them in Slic3r, and then flip the merged file back 180. The quality of prints I get from Slic3r leaves something to be desired though. I'm using kisslicer right now but it doesn't currently have options to print multiple objects with separate extruders. It does have options to print objects with one extruder and support with another though. I checked out replicatorG but didn't like the fact that it is host/slicer software (it uses skienforge as the slicer). I don't want to change host software but if I ever do, I might check out repertier. In fact, I will. But not tonight.

One thing to remember is each STL has to have part of the object touching the bed or it will move an elevated object down to the bed.  Some people just draw a small ring around the part that gets printed on the bed.  It doesn't have to be connected to the part, but needs to be in the STL file.  The ring only needs to be a layer or 2 thick and just gets thrown out.  So make it small to waste less plastic.