Mike I used 1/2" square plexi-glass. There is less flex with square than round. When I finish all the repairs and paint the grill I will install it with all the mounting screws and bolts just snug. Spring is almost here and I won't have it finished for another 2-3 weeks. I plan on facing the car in the sun and letting the sun warm the whole grill up for a couple of hours and then snug the mounting points a little more. I figure the heat from the sun will relieve any stress in the grill and keep it from cracking again. I also agree on what you said Mike about buying a NOS grill. Ozone and where it was stored and how it was stored might as you said make it almost like the one you have. Joe I would like a copy of the Mopar article on plastic grill repair. I have been building model cars and repairing plastic on cars for 40+ years and am not to old to learn new methods. The ones I am using were developed by me but this is the first grill I am doing. All of the car related plastic repair was on interior parts so far. The ones done on my other Hornet's interior are still fine after over 5 years. "Doc"