a life's work in toothpicks and ping pong balls
Weaver writes on his site:
I have used different brands of toothpicks depending on what I am building. I also have many friends and family members that collect toothpicks in their travels for me. For example, some of the trees in Golden Gate Park are made from toothpicks from Kenya, Morocco, Spain, West Germany and Italy. The heart inside the Palace of Fine Arts is made out of toothpicks people threw at our wedding.
If you just skimmed his quote, go read it again. Especially that last bit.