Throttle stick for outboard engine

The throttle is broken on my outboard engine, and I wonder if maybe I could print a new one. I've made a sketch of what it might look like, but it's really a work in progress so far. I need a mechanism that restricts the movement in a good way, so that it stays in a single position when untouched, but can be moved simply by forcing it. I guess a button could be used, but seems complicated. Maybe I could use a spring and some component that pushes against something else. Not sure what a good way of doing it is.

The plan is to have a wire from the motor (similar to a brake/gear wire on a bike) going into the side of the box and fastening the wire to the top screw (grey pin in the diagram). The bottom grey pin is meant to hold the handle to the box and allow it to rotate.

I've added a picture of the current design. This one doesn't have the files yet, but I'll post later. If someone want them now, let me know.