just as alanman says it would cost you a fortune to make a kit yourself. i work with the stuff at work repairing the big bt vans you see (the backs are made of it) last year we had to make a large sombreo hat for a charity event that sat on top of a ford galaxy the cost of that was over 300 quid and we only made it very roughly as it was not seen close up and was only going to be scraped after the event. so again as alan says i would go for a ready made kit and adapt it to suit your own vission. also dont go to your local car spares or halfords ect but try and find a good motor factors \ body shop supplier these can supplie you with matting by the metre and resin by the gallon trust me a gallon of resin is soon gone on a large job.