Change a roof overhang to a ledge or catwalk.

Wondering if someone has changed their 1st floor roof overhang to a ledge or catwalk to help with maintenance on the 2nd floor exterior. The existing is a wooden 3 feet wide overhang with 5/12 slope with roofing material. I would like to make it a 4 feet wide and as light as possible with no support columns.

Any suggestions on materials and design in utilizing the existing?