Step 1: make a plan!
Building a trash boat is the coolest thing since building pepsi can stoves. Everybody is doing it! The first step is to make a plan. How many people do you want it to hold? Where do you plan sailing this incredible vessel? Do you plan on sailing it? What about people power? What kind of junk are you going to use? Do you want to stick to strict "must be recyclable only" guidelines?
Our plan consisted of conversations, occasional drawing on napkins and late night brainstormings. Remember, you don't want to pollute the river or lake in which you plan to cruise. So whatever you decide - give a hoot! Don't pollute!
The picture here shows some old containers we are using for pontoons. But anything that floats should do fine. What about lots of milk jugs? or 5 gallon water containers? Don't buy 'em! Look around! Stop something useful from entering the waste stream!!