I started a CrossFit Timer with a MAX7219 screen, 3D printed the case. I used the Wemos Mini for a change as it had a 5v output. I'm going to bundle this up into a course/project as its quite nice and allows the maker to mess with the code for different intervals. Also, these things are really expensive to buy!
Since taking the photos, I've added another button, and increased the amount of space behind the screen as it was a bit tight!
Watch this space for Details !