I’d guard against the either/or mentality of practice/creation that sometimes can take over people; work hard to keep this from becoming ‘just another hackfest.’ I’d recommend spending a little time each meeting on a specific practice-oriented activity, maybe 15-30 minutes, before starting the work. This will help get people into the mindset of writing good stuff, especially if they are coming from a day of ‘just getting it done’ on Monday at their day jobs.

So, as you build, since you are doing it on your own time, work hard to not just experiment with the new, but spend time focusing on writing great code. Reflect a lot on what you’ve written, so you can use this opportunity to improve your existing skills, not only learn new frameworks, languages, etc.