There are a number of great 24mm buttons, but if you want something even smaller, look into the Sanwa SDM-20 (20mm) or SDM-18. (18mm)
- The downside is that they are both snap-in style buttons.
Focus Attack carries red and white SDM-18s.
Paradise Arcade Shop carries red, white, and black SDM-18s and red, white, blue, green, and yellow SDM-20s.
SDM-20


SDM-18


Scott