I use angle grinders for long straight cuts like taking out the tray for defoaming. For small curved sections, I've tried die grinders, dremel tools, jig saws, and recipricating saws. The best thing I've ever used for small curved sections is actually an aggresive router bit. It's like slowly drawing on paper so you can make any tight corner you want but you can mess up and make it jagged if you're careless.
The vibrating tools are cool but you're still limited to the size of the corner you can make with it.