This Instructable will show you how to make a versatile two-part stool, side table, or planter using (2) 5-gallon buckets, 80lbs. of sacked concrete and CHENG Outdoor Pro-Formula.

Materials + Supplies:

(2) 5-Gallon Buckets
3/4" Melamine coated particle board (13"x13")
1-1/4" Drywall Screws
Blue Insulating Foam / Styrofoam 2" thick
Spray Adhesive (3M 77)
Clear Packing Tape
CHENG Outdoor Pro-Formula Concrete Admixture
Sakrete 5000+ Concrete Mix
8" Concrete Form Tube (13" length)

Tools:

Hand Saw
Jig Saw
Screw Gun + Pre-drill / Countersink bit
Drill + 7/16" Drill Bit
Caulking Gun + 100% Silicone
Sanding Block + Sandpaper (60,100,220 grit)
File / Rasp

Concrete Mixing:

Bucket / Wheel Barrow
Shovel / Trowel
Particle Mask
Rubber Gloves

Concrete Finishing:

Step 1: Construct Lid Form

Construct Lid Form:

Take one 5 gallon bucket and saw the rim off 2-3" below the top edge. This is done easily with a handsaw. How much you cut will determine the thickness of the lid.
Put the top of the bucket on the base board (rim facing up) and surround it with the support blocks (3-1/2" x 4"). Pre-drill and screw supports in place through the base board using 1-1/2" screws.
Caulk the inside edge to make the form water tight. Allow the silicone to fully cure and then remove the excess.
Cut a ring out of 3/4" melamine coated particle board with a jig saw. The ring should fit tightly and needs to be close in size to the inside diameter of the rim. Slide the ring down into the bucket section until it's flush with the rim.
Install four small wood blocks over the top of the rim to hold it down during casting.
Clean out the form and it's ready to pour.

Step 2: Construct Main Form

Construct Main Form:

Measure 1/2" up the side from the bottom of the bucket and wrap tape around the bucket to use as a guide. Cut off the bottom of the bucket using a hand saw. Sand the edge and clean out plastic shavings from the bucket.
Cut a 13" long section of a concrete form tube 8" in diameter. One end is capped with the 2" foam disc, the other with a 3/4" disc of plywood. These should fit tightly into the tube.
Cut the base board from 3/4" Melamine coated particle board. It should be larger than the bucket (13" x 13"). Find the center point by connecting the corners with diagonal pencil lines. You can use plywood, just cover it with clear packing tape so it won't suck water out of the concrete.
Center the knockout on the base board, pre-drill and screw it in place from the bottom. You should be screwing into the plywood disc that is the cap on one end of the form tube. Install the four support blocks and hook the remaining four wood pieces over the rim and screw in place.
Silicone the outside edge where the bucket meets the base to make the form water tight. Allow to cure.

Step 3: Mix + Pour + Cure

Safety:

Wear a particle mask and rubber gloves.

Mixing: For tips on mixing concrete, check out the How-To-Mix Concrete Instructable.

Add 80 lbs. of concrete to a mixer or wheel barrow.
Add 1 cubic foot pack of CHENG Outdoor Pro-Formula admixture.
Mix dry ingredients together.
Add water.
Mix until there are no dry clumps.

Fill the form:

Try to fill evenly around the knockout, pushing handfuls of concrete between the knockout and the form wall.
Fill to the top.
Vibrate the concrete by drop compaction (picking up one edge of the form and dropping it down on the table repeatedly).
Vigorously tap the walls of the form to help drive air to the surface.
Screed flat with a trowel or straight edge.

Cover + Cure:

Place on an flat and even surface.
Cover with painter's plastic.
Allow to cure for 4 full days before de-molding.

Step 4: De-mold Lid

Remove top caps and side supports.
Hold the plastic lid and knock the base board off by hitting it on the ground to break the silicone seal.
Work the concrete out of the lid gradually.
Use a small pry bar, putty knife, or flat head screw driver to lift the wood ring off of the concrete. Be careful not to damage the concrete.
Knock down any sharp edges with a diamond hand pad or coarse sharpening stone.
Use a variable speed polisher to grind the top down and expose the aggregate. (optional)

Step 5: De-mold Bucket

Tilt the bucket on the side and remove the screws that hold the side supports.
Remove the bucket from the base board.
Remove the plywood disc.
Turn the bucket over and place the lip of the bucket on a scrap piece of wood to knock it loose.
Lift the bucket off of the concrete.
Tear out the concrete form tube and remove the foam knockout at the bottom.

Step 6: Details

Aside from color, there's a lot you can do to detail these concrete pieces. Some details are functional and some are decorative, but even something small and simple will make your concrete piece stand out.

Attach rubber stamps to the inside of the bucket with spray adhesive.
Glue fresh leaves to the inside of the bucket and scrub them away after the concrete has cured with a bristle brush.
Make a drain knockout from a piece of foam and glue it to the top of the concrete form tube to make a hole through the bottom.
Cut a rubber bouncy-ball into sections and glue it to the wood ring with contact cement to make a finger recess in the lid.
Glue polished minerals, like an ammonite, to the bottom of the lid form with spray adhesive.
Glue decorative aggregate (precious minerals, crushed glass, etc.) to the bottom of the lid form with spray adhesive, then grind and polish to expose the aggregate.