Pygmy leaf chameleons (R. brevicaudatus) max out at 2-3 inches. But they are usually brown or greenish and don't display the patterns that the bigger species do. I love my pygmys! But you need a particular environment and they cannot be handled at all. The only ones readily available are wild caught so they may not last long if they have heavy parasites or if they're already adults when you get them since they only live ~2 years. But I'd look there if you're seriously looking for a small chameleon. Or there are a lot of geckos that could work well in smaller cages and tolerate more handling. If you've not had reptiles before I wouldn't suggest starting off with a chameleon as they have very specific needs that have to be met.