I thought i would give my two cents. I built mine from left over wood using the ideas i found on this site for a few bucks, not as polished as the others but it holds about 25lbs of feed and works great. I had to build one because local birds were eating all of my organic feed and were hurting my pocket book. I trained them over the course of about 2 weeks. Word to the wise: be sure that if you build it from wood you are careful of where you place it. If it is exposed to water, it may swell and not open or stay open (depending on the materials you use). I basically used the "treadle design theory" and customized my own to suit my needs. Email me if you need any help.