One clever idea is to use them as a mold to make beautiful cement planters. You can use the box as is to create a planter ...

Just as you can reuse them to create DIY flower pots, you can also turn them ... Placed right side up, they make for a fun mold. Once the cement itself has hardened, you'll use it to build a ...

Then the obvious question is: can you cast one in cement? The answer is yes ... by cutting it and then reinserting it into the flower pot. However, you don’t want it to dry out completely ...