How can I build a homemade pontoon boat?

I would like to build a homemade pontoon boat. What are my options. Can I build a frame of marine plywood and fill the thing with something like foam?Thanks for the help. Engineering students here's your chance!|||30 gallon drums and wood frame.|||get a canoe then two foam docks carve the foam so they don't drag take two 2/4s lay across the canoe four u claps now for the foam lay one 2/3 lay on the top and bottom of the foam take two bolts one on the front and back go right Thur leave 2 1/2 in of bolt so the 2by 4 will connect then get a 4 thrust elec motor great fishing|||Guess you could--might not get many passengers though!!