please refer the following pictures and videos for the selection of materials and parts
the following link give some info about the construction
http://www.nasa.gov/pdf/153406main_Rockets_Water_Rocket_Construction.pdf
http://blog.marxy.org/2008/06/killarney-water-rocket-with-video.html
http://www.instructables.com/id/How-to-Make-A-Water-Rocket/
http://wrockets.trib-design.com/index.php?project=TOP&page=design_index
