Materials and Tools:

quick-set concrete
water
bucket
plastic cylinder (empty)
plastic jug (empty)
3 water bottles (empty)
orange juice carton (empty)
4x6" wood beam, cut down to 10"
table saw
circular saw
goggles
tape measure
drill with 2" Forstner bit
palm sander with 220-grit paper
mask
blade

Instructions:

Mix the concrete and water until it has a cake batter consistency.

Pour concrete mix into the larger containers, then set the smaller containers within the center of the mold. Allow the concrete to dry for 3 to 4 hours. While concrete is drying, you can start assembling wood planters.

Cut a standard 4x6-inch beam down to 10 inches. Slice angles off the wood block using a table saw and skill saw to create a geometric shape.

Using a drill and 2-inch Forstner bit, boar out a hole at the top, flat portion of the wood.

Sand the wood block using 220-grit paper.

Apply polyurethane or any color spray paint, and allow time to dry.

Concrete should be dry now. Remove the water bottles, and cut the mold away using a blade.

Smooth all of the rough edges using 220-grit sandpaper. 

Add soil and your favorite plant.