This is a toy, spring-loaded catapult, designed to be 3D-printed.
catapult spring loaded print-in-place (+40m m range) - Makeronline - More Than Fun

It features an intricate, lattice base and arm structures for lightweight, strong construction. The firing mechanism uses a spring and simple lever system to propel a small, round-shaped projectile such as pea or chickpea, Mechanism is also designed to minimize and dampen the recoil. Its compact size makes it ideal for desktop display or demonstration.

Warning: be careful, peas fly far and can hit hard - never aim at anyone or anything that might get hurt.

Printing:

It can be printed without supports, where arm needs to be placed with the narrow beam and cup facing downwards on the buildplate.

I used PLA, 0.2mm layers, but probably any rigid filament would do.

Other material / Vitamins needed:

1x M3x30 screw, washers and a nut

2x M3x20 screw

1x M3x10 screw

2x tension springs approx. 45x6mm

2x ball bearings (10x4mm with 3mm hole) - 623 type works

1x small rubber band or an o-ring to load the trigger mechanism

Assembly and use:

Screw lengths are defined for threaded part length

Insert the rubber band first through trigger opening and then around the respective frame bar, before screwing the frame together.

Springs need to be inserted before fastening the frame, but snapped on the the arm later at any time.

For weaker shots, one spring can be disengaged.

Latch should be engaged only with a thicker crossbar (2nd from the axle)

Manual: SEE PICTURES IN THE ATTACHMENTS!!!