Birdhouses business. Don't be surprised if birds suddenly appear when the prospects of this business are near. Business Overview While building and selling birdhouses may not make you rich, it can provide a good source of additional part-time business income. The only requirements for starting a business that manufactures birdhouses is to have basic woodworking equipment and skills. There are birdhouse design plans available, or you can design and build your own birdhouses. The...