Anyone who has tried making diagrams will at some stage have reached a point where the model is either 3D, or just too “different” to copy, paste and edit. These steps must be drawn from scratch. Various techniques are out there, but for many years I’ve taken photos of the steps and drawn around them in Illustrator.
This, of course, has meant a) taking the photo b) putting the memory card in the computer and c) dragging the image onto the workspace for tracing. Not a hugely onerous task, unless you have to do it often (as authors do!)
My latest brainwave is to open my webcam “capture” software, use the webcam to frame the photo, then I press “print screen” to copy the entire screen to memory. I can then choose “paste” within Illustrator and the image of the screen appears for tracing. Resolution is low, but it’s perfectly adequate for my purposes. Much quicker and no faffing with either the camera or memory card.