Springs are extremely elastic items in Bad Piggies. They take up 1 slot in the building menu and and can't be put in frames. Anything that can attach to frames can attach to springs. They can compact inwards, flattening more than their normal size, or stretch outwards. If they stretch too far, they'll break. They can also bend sideways, also breaking if they go too far. This means that if wheels are attached to them, the wheels will bend sideways. Unlike the similar rope, springs can transmit power from engines.
The default is gray.
The Spring's one-star variation is bronze.
The Spring's two-star variation is rainbow.
The Spring's three-star variation is gold.
When Springs connected together are pulled apart with great force, and being pulled and pushed together quickly and alternatively, they can break apart, and be stuck INSIDE the ground.
There is a known glitch involving TNT and Springs that causes a spring or set of springs to stretch impossibly long, sometimes across the entire screen. This glitch used to be much easier to do, but it has since been partially patched.
There is a second TNT and spring glitch where if you put certain amounts of TNT on the sides of a horizontal spring then detonate it, the spring can sometimes turn 90° and be stuck partway into the ground. It seems to only work for horizontal springs and no other items.
Springs can usually act like a bullet for guns in this game when using TNT with Springs.
A spring appears inside the Boxing Glove. The normal texture has the default spring variant, the 1-star and 2-star variants have the spring's 1-star bronze spring variant, and the 3-star has the 2-star rainbow spring. The alien variant has a blue spring, but since the range is doubled, the texture is stretched out.