how about you use the search feature and look in the appropriate sub-forums/threads first before posting? this question has been asked so many times...
aside from me being an *******... what style of pump are you looking to play; stock class, modified stock class, open class? what kind of pump marker are you looking to build; open class, vertical stock class, modified stock class, MQ valved pump? are you going to use an electric hopper, a standard gravity fed hopper, a 40-50 rd hopper, 100 rd hopper, feed tube/stick feed, or a cram-n-jam?