Going on vacation and don't want your plants to go unwatered? Keep them alive with some paper towels and a glass of water.
There are several ways to make automatic plant watering systems, but this technique is perhaps the easiest and quickest. Roll up some paper towels as tight as possible without breaking them, and dunk the ends in a glass of water and lay the remaining across the soil so each plant is a few inches away.
The paper towels will absorb water from the glass and spread it evenly over the soil. Make sure the end of the paper towel is as deep in the glass as possible to ensure adequate watering.