Chris,
I had to go way back in the archive, but here is the skid plate build:
I got the basic design from the 1964 Monte Carlo Rally Falcon
And after watching the GT Racer episode of the La Carrera Panamericana where the Mustang rips the sump off the oil pan on a topes I had to have one.
It always starts with some templates
Frame Brackets
Insert for core support
Completed Frame work
Final cut on the skin, 1/8" 6061-T6
The finished skid plate is a great place to jack the car. And yes, it gets used!