I just found some old water bottles that i would like to make some copies of.Now my question is,i know how to make the molds for them,but what can i use to make my bottles,i would like for them to be clear as well.
thanks

Clear resin would be best. Plastic doesn't melt well and usually goes cloudy when heated. For cheap resin, look for clear 5-minute epoxy at any discount or hardware store. It works great.