I bought a new rear seat throttle from Chris Welsh. Piece of art it is too. Photos of that when I actually install it; I have to send it away to be anodized black yet to match the front seat DJM throttle.
Anyway, I had Chris turn down the knob a little so that it I can put a cover plate over it if I want to. This is for when I am flying with people and I don't want them to touch (think "little hands"). S imple .025 cover plate held on by four screws will do the trick. And here it is...