In our, once rural, area we have street numbers that are placed by the road to help emergency vehicles.  I had to replace the old post so it seemed like a good time to make it a wee bit more visible for visitors to find.  This bracket holds two solar lights from the local dollar store on a T-post cut and bent to be a number hanger.

I also made a bolt and nut that fit the mounting holes on the lights and won't rust.

Print one bracket, five bolts and four nuts.  One screw is used to secure the bracket to the T-post to prevent the bracket from sliding off.  The screws (and nuts) are printed vertically with the head to the build plate and the bracket is printed on it's side.