Expansion springs are ones that stretch, like a spring in a screen door or a gate.
Bend the rod at a 90 degree angle leaving an end as long as you need to create a hook after. Slip the end into the chuck of the drill between the teeth.
Hold the arbor in your hand grabbing the wire at the same time. Slowly start the drill and squeeze the arbor tight to control the wire. It may take a try or two to get the knack of how to hold it.
Stop the drill before the wire gets to the end because the tip will whip around the arbor in your hand. If your hand is not well protected when this happens, this will be the part where you will be picking up chunks of skin off of the ground.
Slide the spring off the arbor and bend the ends into hooks with pliers.
Yes! it is that easy.
edit: A friend emailed me and told me about a limited travel extension spring. It took me about 2 minutes and a set of needle nose pliers to make these clips to add to my compression spring. (see pictures) The idea is that under heavy loading, an extension spring can deform and straighten right out. This spring can handle much higher loads stopping at a fixed point. Pretty cool concept and super easy to make.