There is a master welder Fred Meyer who has a plane on the eaa ramp and is absolutely top shelf. He also had an automotive Shop near by called precision automotive. I have no idea if these numbers are any good anymore since I moved away. Fred is a great guy.
(678) 377-4800
If that does not work, please let me know. I know how to find him.
Now with all that said, for making jigs, any idiot with a cheap mig or arc welder and some steel can make one. Its a terrific first time welders job. You can even borrow a mig and play with it yourself. Not much to screw up on a jig.