The key to having a sustainable Makerspace is to look at what you’re already teaching or doing, and find ways to integrate Makerspace projects into that.
Lighthouse Charter School created a great flow-chart to help you develop design experience, including questions to ask yourself as you drill down to what you really want students to learn. You can find it on their website, or pages 2-3 of this document on my website.
I like that they include a more structured to more open-ended continuum to help educators decide what will work in a given situation. Try it out for a lesson or project you’d like to improve!