This is a script and instructions on how to run both extruders at the same time to get two objects printed at once. This may have been the starting point for ditto printing on dual extruder MakerBots, but it has probably been superceded by the ditto function in Sailfish Firmware.How it Works -the script basically changes every extruder movement for 1 extruder ( an E000) to an extruder control movement for both extruders (A000 B000). Dimension/5D has to be enabled for this to work. Work Flow -Generate gCode as per usual but use start.gcode with Dimension based Anchor -Run the generated Gcode thru the script -open the gcode with ReplicatorG and print Settings that need to be changed -dimension needs to be turned on in Skeinforge so the we get an E000 code for extruder movements. -the ReplicatorG34/machines/Replicator.xml file needs to be changed so the maxfeedrate on A and B is 4600 instead of 1600 so skeinforge does not throw a fit everytime you generate gcode. I arbitrarily picked 4600- if someone knows the proper number let me know. -in skeinforge alterations tab- remove Redundant Gcode needs to be unchecked otherwise the warmup of the 2nd extruder gets removed -there are two version of the gcode conversion script- one for XP another for Vista and Win7- in the Win7 version you need to edit the script to change the file name that is being converted each time(if someone has a way to do a file dialog like the XP version let me know) -you can either: -use the dimension based start.gode all the time -create profile that uses it the dimension based start.code -use the "use default start/end.gcode" setting in the generate print dialog to control which one you use -the startup gcode also has some warmup tricks I am currently testing. The bed seems to be the slow spot in the warmup so I turn it on at the start of the script. I don't wait for it to be warm at that point simply turn it on, I use 105 degrees in case it is already warm. Then once the homing is done. I wait for it to warm to 100 then turn it to 110 without waiting(I don't think the bed has to be at 110 before we start printing). Then the extruders get turned on and we wait for them to be ready. Know Issues -the anchor gcode of the startup-gcode need some work. -Mac and Linux people are out of luck for the time being- the conversion code is pretty straight forward if someone wants to convert it Thanks to Rob Giseburt for the advice on how to start the process. Let me know if you find any issues. You may also want to check out http://www.thingiverse.com/thing:24195 by JoeyC He made a derivative that is written in C.