As far as bumper construction, we made ours according to the guidelines set forth in the manual. (I know, suprise
)
For attachment we made brackets out of aluminum "U" channel that could slip over our frame without much effort. From there we used 1/4" Push Pins from McMaster similar to part number
92384A036. We found that these worked excellently and almost never came loose during competition. The only drawback is that they're pretty expensive at ~$20 a piece.