We had an interesting situation happen this year at a few of out races.  Many of the cars are assembled using sheet metal creaws to hold the body panels on.  Electrathons can be a rough and vibrating ride.  Well, we had a number of flat tires that were found to have sheet metal screws in them.  It seems the screws fall out durring the race and then flatten tires.  Just a suggestion.  As you are building, use Pop-rivets.  Your car may not fall apart durring the race and it could be your own tires you flatten too.

Aaron

Another thought for teams with sheet metal screws is to cover them with gaffer's tape. If they come loose, they'll stay attactched to the panel and off the surface of the track. Again, rivets are a MUCH better solution, where as mine is just a "temporary" thing.

In the Tampa area all but one of 10 cars car uses pop rivits.  It makes for a tight fit on panels and braces.  
Easy to repair if somethings does come loose.  We have some rough tracks with lots of vibration and have had no problems.  We cary a pop rivit gun and lots of rivits in our race tool box and have only used it once in a year and a half.