Print with 100% infill so it'll balance. Flip the teeter-totter so the bump faces down. Assemble the fulcrum using 1.75mm filament. When assembled, the teeter-totter should easily tip from horizontal to near vertical. Tape the base to the edge of a counter overhanging a five gallon bucket. Bucket base adapter slips onto the lip of a five gallon bucket.
This is a better mousetrap, but no beating a path to my door. It's based on an old farm trick of a baited ruler on a shelf over a bucket.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/3aSZw1VVhIG
Print solid infill to properly balance the teeter-totter.