I have changed the “bucket” to be wider for bigger “projectiles” and added a thumb wheel of easy range adjustment.
But the bigger redesign is the fulcrum. I split it into two parts to be printed easier.
Now the hole for the axle goes now through all the way, so a longer threaded is needed
As mentioned below I managed to break/wear out the spring rather quickly.
Hence I added a beefed up version. This might not be the engineering approach of Leonardo as he had presumably no access to rubber bands. I use my catapult as an office toy and am therefore not too concerned with historical accuracy.
P.S. I will need to redesign the spring and strengthen it. It suffered material fatigue due to tightening the rubber bands to much, because I wanted to increase range and power. Stay tuned!
P.P.S: Here is the original:
Go to Source