I need a new run

For the summer I would like to have a run built for my indoor bunnies to get some fresh air. My Grandad is going to make it for me but I need to give him a design. I have a 4ft hutch that I am going to add to it for a shelter so want something that I could attach to that.

Would people who have anything similar to what I need post me a pic of their set up so that I can get some ideas?