Vectorworks. I usually go to 3D modelling straight away and hone a concept down to the last detail. Later on in a process I support any design with production drawings that would go into the workshop for construction. I make sure and download any critical information from my thoughts, sizes, material and finishes. Sometimes it's  a collaboration between any design and the build team and the meeting of minds. On this particular project, on top of all the technical booth drawings of various assets, I worked hand in glove with the client to get highly specific display boxes, each with unique ports for their switches and to be part of the car display. I ended up having these 3D printed so we could turn up on site and mount them directly onto the car chassis display.  It worked perfectly and no time was lost in fitting the clients hardware. The exhibit became a showstopper and went on to be a successful exhibition and used again on subsequent shows.