i made this a few years ago http://www.vilethings.com/simple_pop_up_introduction.htm
but traded in the pvc ram for a real cylinder. with all the money you're gonna wind up spending to build one out of pvc, you might as well buy a bimba or something from e bay. i just got a 14" stroke 3/4" bore for $17.00.(10.00 s+h). with the pvc, you'll probably wind up spending 20.00 for all the parts, connectors, paint and so on. then you have the safety thing that i'm not even gonna touch right now, but for $27.00, i think it's worth it knowing that its safe and reliable. something like this maybe: http://cgi.ebay.com/BIMBA-STAINLESS...4QQihZ015QQcategoryZ67010QQrdZ1QQcmdZViewItem
but traded in the pvc ram for a real cylinder. with all the money you're gonna wind up spending to build one out of pvc, you might as well buy a bimba or something from e bay. i just got a 14" stroke 3/4" bore for $17.00.(10.00 s+h). with the pvc, you'll probably wind up spending 20.00 for all the parts, connectors, paint and so on. then you have the safety thing that i'm not even gonna touch right now, but for $27.00, i think it's worth it knowing that its safe and reliable. something like this maybe: http://cgi.ebay.com/BIMBA-STAINLESS...4QQihZ015QQcategoryZ67010QQrdZ1QQcmdZViewItem