Orikaso Products of Sheffield, England makes this practical (and affordable at £10) folding picnic set. It's made of thin, foldable plastic pieces that weigh virtually nothing.
When it's time to get the dishes assembled, you unfold them and voila! a liquid-tight bowl, cup suitable for hot liquids, a small platter, even a cutting board.
Perfect for a trip to the neighborhood park or 10 days backpacking in the woods.