k so i would first of all fill the pvc tubes with cement or something to make it solid... cause i had a 10 foot double barrel flat rail made with pvcs and it broke after like 30 runs because of the impact. so do that and then make you battle ship frame out of wood with triangles thrown fucking everywhere to make it sturdy. when you are building the frame, be sure to leave space for you to acces the bolts you will use to attatch the pvc to the wood for quick fixes. also, put atleast 3 bolts on each section over 5 ft (just pulling that number out of my ass, if a section is like 5 and 1/2 ft, put 2 bolts still lol... basically use your judgement.... better safe then sorry right?) ummm, i told you all the problems i had with my rail... so you should be good... other than that, support the shit out of your frame, for example : whereever you have a 90 degree joint between two pieces of wood, put a 45 degree piece of wood to support the joint.
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understand? anyways hope that helped cause it was a long ass reply