Materials:
I bought
http://www.amazon.com/gp/product/B006K8HX56/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1
2x6
1x1
small black self-tapping screws
larger screws
license plate bolts
cordless screwdriver
1/16" drill bit
3/16" drill bit
ruler
2 pool noodles
circular saw
masking tape
square
I boiled the plastic. I decided that I wanted a 13" tall piece of plastic, although I honestly do not know how wide it is. I cut a square edge on the masking tape and put it where I wanted the air dam, from one fender to the other, straight across, with the license plate bolts in the middle of it, and cut another square edge, marking the license plate bolt holes. The distance from the outside of the saw blade to the edge of the [whatever] is 4 1/8", so I screwed the plastic to the 2x6 with the 1x1 on top, so that the 1x1 was 4 1/8" from the edge of the tape. I then cut the plastic to length and screwed it the long ways to the board, with the 1x1 17 1/8" from the edge of the plastic and 4" from the edge of the 2x6. For some reason, I carefully measured the screws, even though it would not make any difference. I cut it again and carefully measured and drilled four 1/16" screw holes 6" apart on each edge and 2 3/16" bolt holes. Finally, I bolted the screws into the license plate holes and put screws through the smaller holes into the bumper. I then shoved a pool noodle between the air dam and the bumper to keep its shape.
I may cut different sized ABS pipes to length and screw them vertically to the air dam.