Improved ratchet & fulcrum of Jay999's remix (https://www.thingiverse.com/thing:3436588) of "Catapult Inspired By Leonardo da Vinci" (https://www.thingiverse.com/thing:3436588) by ollie91297. These parts are replacements of the corresponding parts in the original design/remix.
Now the ratchet is fixed to the fulcrum bar directly, instead of fixing the fulcrum and the ratchet to the M6 threaded rod. The ratchet and the trigger should be placed "inside" now (flipping the A frame).
The fulcrum bar is split in two halves. They will be locked together by the arm, the fulcrum ring and the ratchet.
Fusion 360 design files of the fulcrum bar and the ratchet are also attached. The fulcrum ring was only modified to a larger square hole for more loose fit.
They are designed to be loose-fitting. Wedges are also provided in case the fulcrum ring and ratchet are too loose (I guess this was how they did it in the Middle Ages).
Loose fit (~0.2 mm error) intended.