It's open for any one of us to join and completely voluntary. I worked on my private open source project that has nothing to do with my company on one of the ha

It's open for any one of us to join and completely voluntary. I worked on my private open source project that has nothing to do with my company on one of the hackethons. Since we host the hackethon in the weekend the costs of it are really low. Just the place, and some provisions. I work at a really small company of 5 people. We discuss everything with the entire staff. We have a monthly knowledge sharing session where we do mob programming for fun. We develop a small application just to learn how we each have a different development style. Loads of fun and very educational.