This fits on a 8*14mm lever for useing the brake on a wheelchair. It can replace the old silicone version. This is a bit larger and therefore better ergonomics for the users. You could also fix it with a M6*20 or 25 screw and nut.
Technical
just print it with about 50% infill, 0,6 nozzle, 0,20 layerheight upsidedown (opening on top)