My grandson started to do 3D printing in his college dorm room as a way to make a little extra money for tuition. It mushroomed into a business for which he bought a building. About six years later he sold the business for $80,000. That took care of his debt and he has some left, from which he could pay off his student loans. But he won't do that right now. He was making custom parts for fancy cars. He now works for someone else and has a little more time for his family.