finding a design
for my example, i watched mark rober's "world's smallest nerf gun" video, where he designed and 3d-printed a nerf gun in one piece. i thought this was cool, because it's not easy to launch a projectile when the whole blaster is made out of stiff plastic. his design works by removing some material, allowing the plastic to be bent, so it can store and release energy.
video link: world's smallest nerf gun shoots an ant