Hi folks. I now have my preferred solution to this problem, and like all good solutions to problems, it involves Lego. Basically you can modify a 1x1x0.33 round Lego stud to act as a button cap, and then mount other Lego bits from that. There is a recess inside the 1x1x.033 round brick that fits the DoT3K’s joystick nub perfectly, but you have to cut away part of the brick to make it fit snugly.
http://forums.pimoroni.com/t/pibow-display-o-tron-3000-lego-joystick-mod/138