wjl75 - and here's my approach to the big world of home-made cafe seats:
As I always fancied the clean 'see-through-looks' on bikes, my approach to a 550 cafe seat includes relocating the stock battery plus all side mounted electrics. To give her a more 'racy' look, I moved my tail light to the top of the rear frame bracket.
I started with a basic rectangular-tube frame, bolted to existing frame mounts (air filter housing..), shaped and alligned all panels and tack-welded this assembly to the tube frame. Those cut-outs in the seat pan are for easier access and maintenance of the electric gimmicks. The actual seat area will be made of another flat mild steel panel plus cushion fixed with four Press-Snap-fasteners....
By the way, those mild steel panels are parts of an old PC housing. That means my 70s Honda has definitely Computer technology on board.