The 'Just Mustard' DIY calculator lets you draw any design that you please; all one has to do place the numbers correctly. Disguised as a notepad, this gadget can help you solve those math problems while expressing your more creative side with doodles and notes. The DIY calculator is also a great personalized gift idea, as it can be designed for any occasion.

With many children going back to school in the fall, this calculator would make for a fun surprise that is sure to get them excited for the upcoming year.