I am thinking about putting out some feeders and am considering the "gravity type" as they are pretty much maintenance free (just fill with corn and you are done. no batteries to change or recharge). My question is, does anyone use a gravity type feeder? If so how well does it work/do you recommend? Looked at several different styles on the web. Have even heard of homemade gravity feeders but havent been able to find schematics. Any suggestions?