I think I’ve managed a workable solution with the 3d builder app, for how barebones it is I can still reasonably eyeball a mock up. I’m sure Meshmixer is probably more intuitive and certainly more powerful, but once I’ve loaded my pieces, simplified them, and “embossed” them with a marking for reference I’ve been able to make it serve my purposes. Totally off topic, but I think staring at the 3d builder app and “jig-saw puzzling” is giving me motion sickness. Something that Cura, blender, meshmixer, etc have never done :/ maybe the grid and infinite horizon…. anyway thanks for your help I’m excited to see the diagram you mentioned, here’s my addition of demon buttress’ to the regular Cathedral Walls pack first floor.