This is a bird cage I built for my cockatiel and two parakeets, they have free range in this cage they can come and go as they please, they make several visits to the piggies cage.
This is a great Idea for a Cockatiel, but budgies can get out. It is built wonderfully, and I even took ideas from it to build my Budgies cage, but I doubled the grids to make the spacing smaller. Budgies are not suppose to have any opening larger then 5/8 at the most. The spacings on the grids are 1 inch square.