It's what I did for a living for 20+ years, both 2D and 3D solid modeling...AUTOCAD is anenemydear friend of mine. I use it often in my line of work. I always start out on graph paper though. There is something so cathartic about putting pen to paper. That and I hate sitting in front of a computer in my free time. I do enough of that at work.
Although, the amount of work required to get the chicken living situation to be at the standards I want has proven expensive and time consuming. I’m tempted to go into early retirement so I can focus on the chickens and work as a freelance consultant to supplement my income...
...I almost can't 'design think' without it.

I do some concept sketching with pencil on paper tho too.