One of the advantages of having chickens is that they give you eggs. In making the hens feel more comfortable and making it more convenient to collect the eggs people make nesting boxes in which the hens lay. There are many ideas for nesting boxes, from using old buckets or milk crates to building external additions to the hen house with shingled top and hinged access.
When I built our current hen house, I purchased a cheap 2 shelf book shelf and used it as the nest. They say hens need about 12 inch square and 18 inch deep. This was a little bigger but they have been happy enough with it. It has had some problems that I wasn't happy with and with the use (and abuse) over the past couple years, I decided it was time to upgrade.
I have wanted one built on the outside with the hinged lid and the easy-access nests and had my self convinced to proceed in that direction. There are pros and cons to having boxes on the outside. Building them seems more complicated, keeping weather out becomes an issue. I'm not a great builder and rely on the skills of a long time friend who has had a career in house construction. On the Pro side, you have ease of access and added room inside the hen house.
I have spent some time looking at what other people had done and I think I have found the best of both worlds. That would be nest boxes that reside internally, with only an access hatch on the outside! In my searching, I found a blog where someone had done just that. I stumbled on foxhavenjournal's blog which had nice pictures and details about what they did.
So now I have an idea in mind, I need to come up with dimensions and a rough plan. My 6 hens have had a hard time sharing 2 boxes, I think I'll expand to 3. With a rough plan and a promise of exchanging some IT work with my contractor friend, I can see us getting some work done!