Here's how I did mine - not what you're looking for I know, but might give you some ideas.
First, make a cardboard template on the bike so you know it'll look how you want it. Then lay out the separate pieces on your sheet metal and cut out the shapes.
![](http://i769.photobucket.com/albums/xx334/dogsnuts99/CB750240Large.jpg?t=1260396235)
Bend as needed and weld together (I can't take the credit for this-my father in law is an expert welder!)
![](http://i769.photobucket.com/albums/xx334/dogsnuts99/CB750236Large.jpg?t=1260396354)
Think about how you're going to attach it...
![](http://i769.photobucket.com/albums/xx334/dogsnuts99/CB750237Large.jpg?t=1260396421)
Here's how it looks before upholstering
![](http://i769.photobucket.com/albums/xx334/dogsnuts99/CB750246Large.jpg?t=1260396489)
And finished
![](http://i769.photobucket.com/albums/xx334/dogsnuts99/CB750230Large.jpg?t=1260396538)
I built up the seat with closed cell foam and shaped it with an electric carving knife until I had the shape I wanted, then got it covered in vinyl locally. Total cost about 40.00 GBP ($60 ish?).
Oh, and the T bars have gone in favour of the stock bars and instruments now. Looks much, much better!