Let me tell you first though I love other birds, I hate pigeons and I was trying to make a pigeon proof bird feeder. I failed to do so but my sister tried and she succesed!
Here is simple pigeon proof bird feeder. Designed and implemented completely by my sister. She tried number of designs. Some of them failed as pigeon could easily get in. Some of them failed to attract sparrows themselves! But after slowly improvising the design she could make a bird feeder that could attract sparrows, keep away pigeons. And amazingly she used a plastic net primarily used to keep your house pigeon proof. Pigeon net is cut in squares and tied togather with C-Tie to make a box. A few wholes big enough to allow sparrow to pass through but too small for pigeons are made on each sides. Plastic bowls are filled with water and rice. I noticed that rice is very favourite among sparrows. Pigeons do try to get in but they cant. And here is the success of the experiment !
Look how sparrows try to dominate each other and want to become the owner of the this lovely cage!