I have done dozens of painting programs with students over the years. We use brushes and paint but what do we put the paint in when we paint? Small plastic cups. Although they can easily be disposed of (and recycled) after each class I keep them to reuse over and over and over time, with much use, colorful layers of dry paint begin to build up on the walls of the cups.
Sometimes through ware and tear a cup will crack, or break. In short, they are no longer usable, at least to hold paint. But I discovered another use for them. I saw something somewhere where the bottoms of plastic bottles were cut out to create flowers. I looked at my paint cups and thought, why not these as well? I found that cutting the paint layered plastic with ordinary scissors not impossible but difficult. But a tin snip was perfect for doing the cutting. Then bending the flaps back to create petals I would secure the flowers to dowels with thumb tacks. In moments I planted this forever garden amidst the hostas. The best part is that the flowers bloom all year round with or without watering.