An umbrella is handy. A tinkered umbrella is, in addition, illuminated and interactive.
The info has been verified: it is going to rain, you will need to get the umbrella back out. In order to “maximise the pleasure of the experience of the object” (i.e. take a walk in the rain under an umbrella that is a bit more fun), two students, Shannon Lubetich and Emily Yang, stuffed their umbrella with vibration sensors (the piezoelectric type) and 24 LEDs, the lot interfaced with an Aruindo. When the drops of water touch the umbrella, the pressure they apply on the canvas is detected and it sends the order to switch on the LED linked to the sensor. In practice, it lights up where it’s wet. And it is pretty.
The necessary components, the Arduino code, and the steps to follow (accessible level) are detailed on their page Instructables.
Find all the Do-it-Yourselves.