ocr: What makes a spring springy? All objects, including springs, are made up ofa atoms and molecules. A spring has elasticity because of the forces that exist between its atoms or molecules. If you extend a spring a little, attracting forces between its atoms or molecules make the spring shrink back to its original size when you let goofit. Ifyou compress a spring a litde, repelling forces between its atoms and molecules make the spring expand back to its original size when you let go.