[mom-bot]

Graphics staying on dry method:
This is not quite as fast, BUT they stay on and look great
Utilize or draft a NEMO that has sewing experience, a mentor's spouse or a student with sewing experience. It is even better if they understand basic upholstery construction such as used on furniture. If they are not comfortable sewing the first time on the actual bumper material initally, have them use a piece of inexpensive cotton blend for a mock up to use the cotton as the pattern for the "good stuff."

The iron on's are great, but if they can do a simple zig-zag stitch around the outside of the iron on they never come off. We typically sew ours on - sometimes the day of bagging - but they always turn out.
We have done this since bumpers were instituted and have had no issues with the graphics or the material.

The attachment to the frame is a different story. Due to the configuration of the 'bot changing from year to year it is difficult to have a consistent method for application. The best way I have seen in my six years with the team is we had bolts through the frame, head down and the bolt length sticking up. We then used a drilled bracket attached to the bumper plywood side. The bumper dropped down over the frame mounted bolts and wing nuts were used secure the bumpers. I will see if I can find a photo or a sketch and post it later. It was by far the best we have had so far.