This device adapts a round doorknob to a lever for easier opening by people with disabilities. It has holes in the handle to allow for tying it to a cord (for example, people with amputations or dwarfism who would not be able to reach the doorknob). In this case, it was made for a little boy without extremities; this allows him to open the door to his room by himself.
This design assumes a round, symmetrical doorknob. This design uses a little strip of rubbery shelf liner between the 3D part and the doorknob to provide a good connection and make a non-slip grip. This design clamps onto the doorknob to provide sufficient force. It uses two 1/4"-20 x 1.5" bolts, 1/4" schedule washers, and 1/4:-20 nuts. The design could be used with any similar hardware (i.e. changing door parameters may require a different bolt).