Many people build their own launchers but I decided to purchase the PITSCO Aquaport launcher because it appears to be very popular. I am concerned about safety when doing this activity and did not want to worry an accident was caused because of a launcher I had built. The rockets I have used for groups are based on a smaller bottle and have lots of foam on top. I use a good quality bike pump with a gauge and do not pump to excessive pressure.
This is a good activity because the build time is short and the rockets are so fun to watch when they launch. On my website article there is a PDF file template for the fin pattern I used for the 24 ounce bottles. Normally I cut the fins out ahead of time with a hotwire foam cutter sold for creating model railroad scenery. Water Rockets Article on Website I have also created a couple of videos on water rockets.