nest mould

Place the outer walls on the sphere an close eyerything with bolts. If you like you also can thighten up the edge with some duct tape to prevent leaking of the plaster. I used very fast hardening plaster and you should too. 

I designed this form so that I can make my own bird nests and in my case espacially for martins. 

The design works great and demoulding is very easy. I placed the nests under my roof to protect the nests from getting wet. Shortly after I installed the nests the martins came to stay for the summer and quickly accepted the nests. 

You can cut off the cylinder because it's only purpose is to make sure that there is no air inside the mould. (When moulding and the plaster is filled to the top I recommend knocking on the walls to really bring out all the air.