Space Blocks, a fun physics based game where you need a safe hand

Staple parts and blocks to build towers with a certain height. You need a safe hand or you will fail!
Grab parts with your mouse, and drag and drop them. Staple them as high as you can. You at least have to hit the red line. Parts must not hit the left and right border. Drag the empty space to get more parts. Click on "Ready" to get to the next level.