I have designed a 3-D joystick knob for electric wheelchair users that is easier to grasp. They are about twice as the size of the default joystick knobs. I have gone through a few iterations of joysticks to come up with what I think is a great fit for many people. They may require reaming with a drill bit, dremel, or sandpaper. I have recently designed a cupholder as well. The cupholder is for use on Unitrack rail systems and only requires the set screws.