Definitely worth it. Sometimes I make little things, like I got a new tool that has a difficult adjustment, but printing a knob made it comfortable to use. I got a new phone last week and couldn't find a rubberized case I liked, so I designed and printed one this weekend which fits snugly and provides a much better grip. I've made cases for other projects, even built a weather station. The biggest project I've done is a star tracker (OpenAstroTech) which holds my camera, most recently used during the eclipse in April. Sometimes my printer may sit idle for almost a year, sometimes it prints constantly for several weeks, but it is a very useful tool worthy of a permanent location on my workbench.