Floats purchased at the store are great, but they're often expensive and it's usually just a matter of time before a hole appears. You can build your own raft for almost nothing. In fact, you probably already have everything you need to make a raft that will weigh next to nothing and sail down a river.
Save your plastic soda bottles. Whether they are 2-liter or 3-liter, all must be the same size. For a small 6-foot by 4-foot raft, you will need 120 bottles. If you don't have enough saved, visit a recycling centre and ask if you can purchase used bottles. Make sure you have the lids or caps for all bottles. You will need them to secure air in the bottles and keep water out.
Line up the bottles in a large open area, with five rows of 12 bottles lined up next to each other. You can construct your raft inside or outside. But if you choose to do so inside, make sure your door is big enough for you to get the raft outside. Make sure the bottle surfaces are clean. Align the bottles so the caps or lids are touching. Use a disposable brush or roller to apply contact cement to the caps of two bottles. Hold the two together to allow them to cement. Let the couplings dry for at least five minutes.
Make five more identical pairs. Cement the six pairs together, bottom of bottle to bottom of bottle, until a straight line of 12 is formed. Make three more rows of 12 in the exact same manner. Place the four lines of 12 bottles beside each other, and cement them together.
Once your raft is constructed with contact cement, use duct tape to wrap the bottles from one end to the other. This will make sure they stay together and provide extra support.
Repeat the same process from beginning to end with the remaining 60 bottles. Place one of the bottle platforms on top of the other, as if stacking mattresses. Secure the two together by wrapping them in duct tape.
Place a piece of two-inch thick styrofoam cut to match the measurements of your raft. Place the styrofoam on top of your platform of bottles, and secure it with duct tape. Hop on, and sail away.