Clients frequently ask whether it is possible to be granted a patent on an invention that does not contain new components. The answer is “yes.” The majority of patents are in fact “combination” or “improvement” patents. It is rare that someone creates something as new as a transistor or another fundamental building block technology. People frequently create new machines or articles of manufacture based on existing technologies. Take a look at the attached article titled “Self-Taught Inventer [sic] Creates Homemade Electric Wheelchair”
http://www.weirdasianews.com/2009/11/27/selftaught-inventer-creates-homemade-electric-wheelchair/
In essence, his creation is a combination of existing technology. The bare bones elements of his creation include shaped materials in various components, wheels, and electricity. The video shows him using commonly available tools to build his creation. We know that metal of various shapes is not new. We also know that powering the rotation of a shaft via electricity is not new. However, a wheelchair with a shaft attached from which multiple wheels are connected that enables the injured or elderly to descend stairs without assistance is a combination of existing technology that could form the basis of patent application.
Assuming the wheelchair does not already exist, the main question to ask is whether the new combination of features is nonobvious. In other words would a person of ordinary skill in the technology have combined the features to produce the unique item on the filing date of the patent application? If not, and the new combination complies with other aspects of patent law, a patent can issue on the new technology.