When I build a cage I print out all of the pictures I have saved off the internet of cages I like. Then I paste them on poster board with the sane views, ie front, rear, interior....
I then rough sketch what I want the cage to look like, take some measurements and start bending. I used a lot of styling of the famous flying banana.
If you are asking about the little additions. I would add tabs for a whip and a car to car radio antenna, add tabs for an aluminum roof, tabs or bungs for rearview mirror and lightbar. Tab for a gps, oh-shit bar for all seats, tabs for window nets, tabs for helmet or headset hangers, dome light tab or hole in cage for wiring, tabs for overhead console or switches, the lust could be endless.