Make a swallow house

You can get examples of home swallow designs here

If you look at the selling value of swallow nests, which gives a lot of hope to be able to have a life that is very feasible in the future, making many people who are willing to have a swallow business. However, with such a large cost, especially in building the swallow's house building, what can I do again, that this makes many people undo all of their intentions.