ANY CUSTOM SPEARGUN MAKERS OUT THERE

i work at a custom door shop, that has mahogany everywhere so i decided to make a blue water gun. i don't want to buy what i can make so any help on finding a good blueprint would be great. i have searched alot of sites that offer to sell all the componets, but no blueprints any ideas?i am going to pick up a riffe to look at specs & rigging but i am not sold on the build.