[GeeTwo]

We have used paint and the AM heat-seal numbers, and have no complaints with either one. Embroidery sounds great. Use short stitches, to reduce the stress and damage when those bumpers get used for bumping. And of course, some seriously strong thread. Hmmm.. can you do embroidery with an opaque monofilament?

For securing, the main thing is that you can switch colors very quickly, and remove and replace reasonably quickly in case you need to get re-weighed. Our rookie year, we used clevis pins and cotter pins, which went in from the bumpers through the chassis; a nightmare. We did "bumper covers" in one color our second year, and were not happy with the appearance of the results; YMMV. Our third year, we had gaps in our bumpers both fore and aft, and secured with four (10-32?) wing nuts. We had four bolts sticking up out of the chassis, dropped the bumpers onto them (which made close contact with the frame perimeter; we had no protruding bolt heads at that altitude), and spun them down. We were double-teamed by defenses in a few matches, but the bumpers stayed in place. This year, we will probably do something similar, but with nylon locking nuts and an electric nut driver (with a hand nut driver in the tool bag as backup!). We will probably have more than just the four bolts to handle the lateral stresses, but only about four nuts to hold the bumpers on.