Advice for a disabled ready stick?

I'm a quadriplegic with no finger movement altho I can move my hands and use a joystick by putting the stick between my fingers. I'm looking for advice on possibly creating or modifying an already existing handle. ATM using a ball top works but its not the best. I'm fine moving right, but moving left my hand sometimes slips off the stick because I have no grip. What I'm looking for is something like this:

I would be able to just place my hand on top and the raised edges would keep my hand from slipping. Thanks in advanced for any help.