Whether you are using plastic balls or rubber duckies the principle is the same. The plastic ball or rubber duckies are numbered with an indelible marker. People buy a number on a duck or ball. A duck or ball is then selected from among many with the numbers on the selected ducks or balls being the winners.
The selection of the winning ducks or balls is made into a spectacular event.
Typically rubber ducks are tipped into a watercourse from a tip-up truck or something similar, preferably from a great height. They are eventually funnelled into a narrow chute so the winning ducks can be selected.
The other option is a swimming pool with the winning ducks or balls being fished out with a pool leaf scoop or something similar. Preferably the person doing the scooping would be blindfolded with the fun of trying to make sure they don’t fall in.
Another option for the balls is a ball pit and having a blindfolded person dive in and select the winning balls. There is also rolling the balls down a hill with warning barrier netting or hessian fence catching the balls at the bottom with just a narrow opening to let the winning balls through. If the balls are a little slow help them along with a leaf blower.
You can get 200 plastic balls for $15.99 on Ebay (September 2016)(8 cents ea).
Why so much?