You make it sound easy...lolA radius gauge and calipers are a lot easier to work from in my experience. The beauty of 3D printing is if it takes a couple of iterations to get It just right that’s fine.
Even a photo, calibrated to the right size, will do.
My lad wants me to create this for him so I am back looking around for tutorials and inspiration.
What's frustrating is I was going to use the Xmas break to get my head round it but the kids are back to school on the third.