Sorry, I didn't forget, just been busy.
This should get you 99% of the way there (even though my high school tech drawing teacher would be outraged).
http://s46.photobucket.com/user/annaandnathan/library/Bikestuff/KX125C?sort=3&src=wap&page=1Three dimensions are missing:
1. The radius of the outside edge onto the rear mounting tabs.
2. The radius on the rear mounting tabs back onto the body of the brace (between the mounting tabs). Probably R15.
3. The distance between the front and rear mounting points. I'll check tomorrow and post back.
The rectangular holes are all the same size/shape.
The three forward "rungs" are all the same width.
And after measuring mine, I remembered that it has been linished down - it should be 3.0mm.