When I decided I wanted to make a "real" nest for my VT project this month, I started looking for some good tutorials to help me. There were a few really good ones, but most of them included more work that I wanted to do.
I left the bottom of mine uncovered so they would sit flat on a table or shelf. If you will be putting yours in a tree, I would suggest covering the bottom.
In the end, this project cost about $11 for 4 "real" nests...just under $3 a piece.