My dh has given me an early anniversary present (Feb. 14th). He just finished building it today. He still has to afix the drop lights above the "windows" for heat but they will be snug and safe. He built me a 22 inch deep box with a removable divider in the middle. It is six feet long. He then made it 36 inches high as I am only five feet tall and he wanted it to be a comfortable reach for me. When my newly hatched chicks have feathered out I will put them in there instead of the house..thus making more room for more hatchlings. He used all scrap lumber he found around the place for it.
