I was at work and the center of the cheap plastic button of my pants broke off. Fortunately I had access to tools at my job and decided to make my own button.
To duplicate my version you'll need:
1 Button-sized coin
1 Zip-tie fastener
Drill with drill bit
Vise or other tool to hold the coin
Step 1: Drill Holes
Using a vise, grip the coin by the edge and drill two holes large enough for the zip-tie fastener to fit into them.
Step 2: Make Holes in Pants
With a very thin or sharp object, puncture two small holes into your pants where the button would go. (not too close to each other)
Step 3: Fasten Coin
Fasten the coin with zip-tie as shown.