This is my version of a dual color/extrusion prusa i3 with a cyclops hotend (single nozzle).
That printer was for some people who want to use pla+hips as support material (yeah I know that is not a good combo...).
But after some (a lot...) test I was able to print "correctly" PLA+hips.
The cyclops hotend is not the best hotend for PLA... I have to use a very short retraction (only 3mm) to prevent continous jamming...
While for the hips I could use retraction up to 9mm. Printing temperature was 210° (so it could print PLA and HIPS without changing temperature), and 65° for the bed.
As I said PLA+HIPS is not the best combo... the 2 materials are really different...
But as you can see it could work.
If you want to download the file visit my website at the link below ;)