The 6 oz. Yoplait yogurt cups sold in the US have two odd features: they're wider at the bottom than at the top, and there's a flange around the base that raises the floor of the cup about 3/8" above whatever it's sitting on. The wide base makes it surprisingly stable, and the raised floor gives the blade tips a place to lodge without causing or risking harm.
Being wider at the bottom is apparently part of Yoplait's trademark. But this creates a hazard for skunks and other small animals wildlife with small heads and strong yens for yogurt. Some skunks and squirrels have stuck their heads into discarded Yoplait cartons to get at leftover traces of yogurt and not been able to get them back out. This is hilarious to watch, but not so much fun from the skunk/squirrel point of view.
There was a lot of public concern, and Yoplait added the flange to the bottom of the cartons so the critters could grab hold of it and pull themselves out. This and other design changes made for the purpose seem to have helped, but not eliminated, the problem (Snopes discussion: http://message.snopes.com/showthread.php?t=34426 (offsite link)). Whether the problem ever actually is or was as widespread as the public concern is not entirely clear; but still, keeping Yoplait cartons away from skunks is probably a good idea.
Having a safe, convenient place to keep on your workbench to keep your Stanley knife and other tools is a very good idea. Using this "Stanley Cup" will help save the earth by keeping empty yogurt containers out of the landfills and by reducing the use of medical supplies needed to treat a nasty cut; and it will help keep skunks out of trouble.
Step 1: What You Need
6 oz. Yoplait yogurt cup
Stanley knife or other smallish-to-middling-sized hand tool
Skunk is optional. :)
If you want to make a paper or Tyvek cover, you will need:
Paper or Tyvek
Cover Template from attached file (or willingness to fiddle around with the paper until you get the right shape)
If you want to make a duct tape cover, you will need:
Scissors (optional, but it's much neater with 'em)