After solving the bulk issue (see previous 2 posts) on this collaborative project, we moved on to the next challenging step: top welt on the curved face.
I almost never make welting ahead of time; usually I make it and apply it all at once. With this somewhat stretchy fabric, we really didn't want to sew the welt and risk having it pucker. Double-sided adhesive tape is used to "baste" the welt together before stapling. Starting from the middle, the 3" bias strip is pressed into place.
It's eased around the curve; here I'm feeliing for where the welt is going to sit and make sure it's perfectly smooth at that spot. This really would not work with the fabric cut on the straight.
Once the front feels right, the back of the strip is pressed down against the tape, making sure all the puckers are behind where the bias strip is going to roll over the welt cord.
Then another strip of double-sided adhesive tape is applied, and
starting in the center again, carefully roll the bias strip over the
welt cord and press in place. At the curved end it just pops itself
into place, and the only thing to worry about is keeping the fullness to
the back of the welt cord so the front is smooth. 
The staple gun is used to shape the welt at the curve, because there won't be any tacking strip there. 
This upholstery fabric is so heavy, staples were used on the curves to keep it under control. Normally we like the staples to be invisible.
The bulk-reduction technique worked perfectly!
Just to add to the fun, one of the windows was a bay The boards are hinged together. Here also staples were needed on the top of the board to make sure the dustboard cover was secure. Nice!
