Is coffee mug theft a problem at your job? If so, you may want to take a look at Efrat Gommeh’s latest design… the Lock Cup… which is basically a coffee mug with a hole in it. When you want to use your mug, you install the plug/key and the cup will not leak. When you are done… pull the plug/key out rendering the cup pretty much useless. Combine this with the theft preventing pens and you are set.
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Reminds me of this medieval puzzle mug. You know the one where if you didnt know the trick of which holes to plug up you couldnt use it. Hey that could be made into a dirty joke somehow!