This Instructable will show you how to make concrete boxes using cardboard and duct tape. This example is a planter, but they could also be useful as storage.
CEMENT PAVER PLANTER BOXES: All you need are a few - pavers, - landscape-block adhesive, and a little time. Wait 24 hours for everything to cure and you're ready to move your new planters into place and fill them with dirt and greenery.
IKEA Hackers: Large concrete planter from kid's chairs
Turkish Mediterranean Residence - mediterranean - Landscape - San Francisco - Shades Of Green Landscape Architecture
Do this but then fill it up solid Concrete sphere diy