Make cement cloth planters. Approximately a water/cement ratio. Add drainage holes in the planter before it completely hardens to prevent cracking. You may also want to apply a couple coats of cement sealer after the planter is dry.
Wood pallet sandbox, with bench seats that unfold to cover the sandbox! I hate sandboxes bc it's like an outdoor litter box for wild critters. Love that the cover will keep them out! Hubby is going to hate that I found another pallet project :D