Through a code club and makerspace that I run here locally in Oslo, Norway I have developed a few Arduino projects that I think are nice in that they show off projects that are doable within a reasonable amount of time. By “reasonable” I dont mean a few hours, but projects that can be completed within a few months with kids that are motivated to learn and tinker with both code and design.
The first attempt I had at the code club was to build and program a game using an 8x8 LED matrix consisting of 64 WS2812b LEDs. Since then (roughly 2 years ago), the project has moved into the 3D printing space as well, with the box now being designed and 3D printed.
If anyone would like more details on this project, please do tell me and I can provide what I have - links to 3D designs, source code, or any other information that might be relevant.