This is a DIY little trebuchet I created for fun. The original design had a flaw in the payload delivery system so I adjusted the arm to add a little finger Printing the sling isn't necessary but I wanted to play with flexible materials. Any cloth or maybe even paper might do! The holes for strings are 2.5mm wide. The sling strings should reach from the Arm hole to the lever arm, and the basket should be able to clear the base when it's attached to the arm and the latter is in the vertical position. I glued the holders to the base with simple universal glue. Don't forget to print 2x holders.

Use and play with responsibly! Even if it is a low power device, it may still take an eye out. Works fairly well with standard size marbles.