The problem is that special needs are - by definition - special. You do not have to work in this field long before you encounter a client whose needs can not be met by an existing product.
The foil switch allows for rapid customization of switch access. It allows for prototyping abilities not found in commercial products. The therapist can quickly (in the field) evaluate many different sites for switch access and experiment with various ranges of motion. It also means that a therapist can make a switch custom-tailored to an individual. The user can become the switch.
The foil switch activates with an extremely light touch, which is great for clients with low muscle tone. It is also very cheap to make - it costs about $1 for a switch (some commercial switches cost hundreds, but most are under $100 USD). It follows a "make once, use many" approach - once the wiring harness is made, it can be reused again and again and be instantly customized by changing the shape of the aluminum foil.
Over the years, it has proven itself to be an extremely versatile tool and we have used it with many clients, both adults and children.