This is a model of an imaginary stone-throwing device called a Springbolt. It's sort of a combination of a stone-bow type crossbow and a cannon. It should be close to 28mm scale for miniatures, and is intended to be used on the deck of your favorite Spelljammer or fantasy sailing ship.

**Update: This file has been REVISED 7/23/23. Springbolt V2 has eliminated some of the dead spaces in the model and simplified the structure overall to make it easier to support and to print. I orient it barrel-down, with the yoke near the top. Your mileage may vary.