My daughter is interning at a day care. They needed aprons so I made 18 of them using this pattern I found. The neck strap is an elastic/fabric tube and the waist strap attaches on one side with velcro. That way the teachers don't have to help the kids put them on. They went together really fast.
The pattern was on
http://sewliberated.typepad.com/sew_...tutorials.html