Here are some pictures and an explaination of my home made door opener. It only opens the door, not shut it, but thats fine with me. I always check on the coop at night, so closing it is no problem, but hate to see the hens stuck inside until I get up in the morning which can be a bit late on the weekends so its nice to have the door open automatically. The main expense is just a wind up clock that must have a wind up knob for both the clock and the alarm. If it only has one wind up knob for both the clock and alarm, it wont work. I got my clock on ebay for about $12. The other things you need is some string, a spring and some wood or plastic pieces. The first picture shows the mechanism that holds and releases the door. In this case I took, what I'm calling the door latch, a 3"x 3/4" piece of 1/4" plexiglass, (could be wood) drill a hole in the middle as the pivot point with two holes on the edge at each end which get hook eyes, one for the string and the other for the spring. If you look at the picture you can see the spring attached to the top hook eye and the string on the bottom one. The other string you see in the picture goes out the door opening and is attached to the door so it can be pulled shut from inside the coop. Also, notice the screw on the left side/bottom of this plexiglass door latch. This keeps the door latch from swinging into the door opening. In the next picture the door is shut with the door latch drawn in place holding the door closed. The string attached to the bottom of the door is pulled, causing the door latch to pivot into a bracket in the door. The last picture shows the other end of the string hooked over the alarm wind up knob. When the alarm goes off in the morning the knob begins to unwind, the string slips off the knob, the spring pulls the door latch back into the vertical position and the door swings open. My door has a weight rigged on the outside to make the door swing open but it could be done with a spring as well. Its clearly not as fancy as the $200 open and close models but for around $15 it works just fine.