Back during the previous period of having Red Squirrels visiting here on a frequent basis, we took advice on design & materials to build an artificial drey. We *think* it was used, but then we started seeing greys so took it down [helped by some appalling weather !].
Looking up inside --- the hole you can see is the "back door"
By Mid-July 2026, this has now been cleaned [with animal safe disinfectant] and refurbished, including with new bedding - dry moss, dry leaves, dry straw and some pet grade wood shavings. And will shortly be placed / secured in a suitable tree.