When I built mine, I angled the corner braces, providing an open center so that I could use a creeper and slide under the car. It's proven to be quite useful.

7335185-jig.jpg (4822 downloads)

1968 GTX hardtop
1968 Sport Satellite Convertible 383/4spd
1933 Plymouth coupe
2002 Ram 2500 oil burner 4x4
2015 Grand Cherokee
2013 Challenger
1957 Chrysler Saratoga


Man...I need a bigger freakin' garage.