I just traced a pattern off of an apron that I already had. It falls to about my knees, and is about half of my hip measurement around. I think it'd be nice to have a wider one. It's surprisingly narrow at the top - only about 8 inches or so. For the straps, you could make fabric tubes like I did, or save a LOT of time and just buy ribbon. I also reinforced where the straps attach.
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