Where To Buy External Nest Box?

[TheBrumstead]

I need an external nest box. My husband built the 4x4 Purina coop, but him and my uncle decided I didn't need an external nest box... Now I have a 1 yr old RIR who won't let my 13 wk old BR roost. I am getting two more in late July and I'm afraid she won't let them roost either. I am using a covered cat litter box for a nest box and it works well, but takes up a lot of space. I can't put a roost over it. If I can get an external nest box, I can add another roost. The only one I have found for sale is the Ware Chick N Box. It seems to have good reviews, but I've only seen it attached to Ware coops. Anyone know of another one? Or have you attached one to a different coop?