WubbiConcepts | Minecraft: Compact smooth stone generator v2 @WubbiConcepts | Uploaded 12 years ago | Updated 17 hours ago
Here's a newer verison of my smooth stone generator.
More pistons, but now only 4x4x3 and with integrated switch to start/stop/reset the system.

Also, have a look at this design (survival-friendly):
http://www.minecraftforum.net/topic/1065359-bud-based-smooth-stone-generator/page__st__20#entry13224092