This is an f2k style floating arm trebuchet. My son loves launching stuff with this thing, but he needs help loading it. For office wars it can be adjusted to launch objects high over cubicle walls and vanquish your opponents. One of these days I'll post a video of it.

The frame stands about 8" tall by 12" long. It can easily launch the small golf ball included in the files a good 25-30 feet with the right sling/pin and counterweight. This must be printed in pieces and assembled, with some hardware and other items required for assembly. Press fits are designed for 608-2rs bearings.

What to print:
Base_front 1x
Base_rear 1x
Frame parts 1 of each (4 total)
Arm 1x
Top pieces 2x
Trigger shaft 1x
Trigger wheel 1x
Wheel 1 1x (optional)
Wheel 2 1x (optional)
Wheel 3 2x (optional)
Wheel 4 2x (optional)
Ball As many as you want (optional)

What to Buy:
M8x150mm threaded rod 1x (I used the one from the spool holder that came with my printer)
M8x80mm bolt 1x
M8 washers 4x (to retain any larger washers used for counterweight)
M8 nut 9x
Large washers 10-14x (25-40mm outside diamter, for counterweight)
Thread 2meters or so, for sling
Cloth 40x80mm ish, I used microfiber, for sling
Paper clips 2x (medium-large size)
M4 or M5 washer 1x (for sling to pin connection)
608-2rs bearings 3x

Assembly:
If you printed the wheels (I really didn't notice much of a difference in performance with or without them, they probably help a bit with keeping the arm centered on the frame) then snap them onto the bearings. Press two of the bearings with the small wheels onto the arm shafts. The other one goes on the M8 bolt at the rear of the frame. The frame is intended to be pressed together. Center the M8 threaded rod on the arm and retain it with nuts. Add counterweight. Slide it into the center slots on the frame and install the top pieces. For the pin, cut a 50mm long piece of paperclip, heat it up with a lighter, and press it into the small hole on the end of the arm. You will need to play with the length and angle of the pin to get the ideal throwing arc. For the trigger, use another paperclip and bend it/ cut it to the proper length. The sling is a rectangular piece of cloth with holes in each corner, and 150-200mm thread doubled up for each side. One side of the sling is attached to the thru hole at the end of the arm, the other is attached to a small washer that goes around the pin on the end of the arm. You'll figure it out.