We use left over decking, and I have a ladder or two. The decking is about 70 ml x 19 ml. This allows them to sit their feathers down over their feet in winter. A fake egg will give them the idea of where to lay, in one of my pens I have a milk crate with a side cut out, turned upside down with some hay on the ground. It is one of the preferred laying spots. Pine needles are pretty good too . Btw, if you have any golf balls laying around they are just as effective. Another cheap but good idea is those heavy duty caterers type buckets. Drilled through the bottom, straight to the wall and off the ground. Put some hay in and presto, nest box.