Hi With regards ruby it would pay to post your enquiry in the developers' forum to get more responses Personally I am in a similar position, learning ruby, building DC to be used with code, interest is framing With regards swapping, and cut list consider the example again with a group of Right end components if you copy the side DC and replace the geometry within one of the Right ends with it, set the DC to required parameters, then right click, outer shell then explode, all updated and can be seen as complete in cut list Cheers Philip sides.skp