level of difficulty:
The Ruby Amp is a great little battery powered solidstate practice amp. The design is based on the Little Gem design which in turn comes from the Smokey Amp designed by Dave Stork on www.blueguitar.org. The design uses relatively few components and is a good DIY project. Cigar box guitar maker J.K. built a Ruby Amp but found himself hunting for a suitable enclosure for it. Then he noticed an old magic 8 ball that looked just right with a perfect sized hole for the speaker.
Is this a good amp? ...<Shakes ball vigourously>... Signs point to yes!