Ukrainian Gears' Mechanical Box is a 3D plywood puzzle that requires no glue or special tools to assemble. Just your ingenuity. Or ability to follow the instruction manual. I think it might be the perfect gift for Mother's Day. I buy the puzzle, spend precious time putting it together, stick a thoughtful little note like, "Hi Mom. You're nice" inside the box, and then present it to my mama to rotate the gearwheel, which will lift the lid and reveal my message. She'll be so touched by my generosity and thoughtfulness. She won't just prominently display the puzzle on her fireplace mantel, but from that moment on, she'll move it around the house with her. So it will always be in her direct line of sight, and so she can regularly re-open the mechanical lid to relive the moment she first received it.
The only problem is that once I get the puzzle all built and set up, I'm probably going to want to keep it for myself.
The Mechanical Box model measures 7" long x 3.6" wide x 7.4" tall when constructed. Its box is sized to hold standard business cards.