3m, sem. etc brands sells a auto body plastic weld it's like a caulk tube for mending plastic bumpers .. all you need is a plastic mesh and a puddy knife to spread it on might need a special caulk gun too... but that what they use. For plastic bumpers when people get in car accidents... they sell it at tcpglobal.com if interested in it...I think it for making plastic tabs to hold the bumper on... strong stuff... if any thing search or ask around.. this is all depending on type of plastic you got for the tub there are ways to find out...just a heads up cause you need to if welding with heat or puddy ...