“Pick up milk.” “Feed dog.” “Finish homemade nuclear sub.” Like many people, I can’t function without writing little reminders to myself. But using one paper sticky note after another causes a lot of clutter and can be pretty wasteful. Instead, assemble a bunch of surplus parts into a digital note system for your kitchen or office. Just write out your message with your fingertip on a computer trackpad, and it appears on an LCD screen.

When you’re done, press a button and the screen is erased. Add a rechargeable battery and an enclosure, and you have unlimited (and eco-friendly) note-making capability. The project does require some computer code to drive the LCD; you can copy it here. If you can just remember that, you’ll be good to go.