Does your office lunch seem a bit bland? A contact lens case is a nifty way to store small quantities of your favourite condiments.
All you have to do is fill one or both sides of the case with the condiments of your choice, seal it well, and toss it in your lunch bag. This can be particularly helpful for sandwiches, since it lets you spread your mustard at lunchtime rather than having the bread get soggy.
If you wear contacts, you'll have dozens of these things lying around, and this is a clever way to put them to use. Check out the source link for some more handy uses for contact cases.
9 Ingenious Uses for Your Spare Contact Lens Cases [WonderHowTo]