Instead of putting a paint smear across the outside of a can to mark the level of paint left inside (which can be messy and obliterate the label), use a rubber band instead. Put it around the can and roll it down to the level of the paint. Just by glancing at the rubber band, which is visible all the way around, you will know how much paint is left.
Accessories available can turn your plastic 5-gallon buckets into handy tool carriers. Another way to put them to use is for storing extension cords. Cut a hole near the bottom. Feed the female end just through the hole from the inside. Then coil the cord into the bucket for easy carrying. You can also put small project parts inside of recycled plastic peanut butter jars and store them in a bucket. The jars are easy to carry around, won’t break, and let you easily see inside.