I want to create a parametric mvpart for a watersource heat pump. Right now I have blocks created for every size and every supply and return air configuration. Can anyone help me out in creating the 3d model in the work plane and then add the duct and pipe connectors in the locations per a cut sheet?

I have these drawn in 3d blocks and have created block based mvparts but I can not add the extra sizes I need. I have started post on that problem already.