Remix of http://www.thingiverse.com/thing:79502. Tweaked to have a smaller footprint. This is a nice cheap battery holder to use for small projects and prototyping. Wires to your project just go into the holes on the front and back of the holder and are press fit in place when you insert the battery. No soldering, no hassle. ~$.03 to $.05 in material costs.
Strip at lease half an inch of wire to expose the contacts for the battery. For the back half, insert the wire from behind through one of the holes, run it along the channel guide and back out the other end. Clip off excess. Repeat the process for the front using the notches and channel guide there. Insert CR2032. The fit should be snug and the wires will be held in place.
See more detailed instructions and pictures here: http://www.thingiverse.com/thing:79502