How To A One Minute Timer?

One idea to make one could be to get 2 cheap plastic and attach the both bottom ends of the cups to each other (like an "hour glass"). You could then punch a small hole where the cups meet and fill the top one with fine sand. Time how long it takes to run out and then adjust the amount accordingly until your have the right amount of sand for one minute! Once you have the right amount, make covers for the top ends of each of the cups and voila! You have a minute timer.

Use lots of rubber bands and a stick