This project takes discarded tanks and makes stylish planters out of them. The tanks can be anything from disposable helium tanks to water heater expansion tanks, but please respect the dangerous nature of pressure vessels and flammable gasses. Never attempt to cut a tank that is under pressure and under no circumstances use hot processes to cut tanks that once contained flammable gasses. Very few people want to die in a freak explosion.
Step 1: Gather Your Stuff
First you need a tank. We used a discarded water expansion tank, but disposable helium tanks, expired fire extinguishers and the like are readily available and will work fine.
Work holding strategy. You need some way to hold your materials while working on them. I used a vise (not pictured) but clamps, straps, duct tape, and brave friends are all possible solutions.
A length of 2x4 lumber (not pictured)
Pencil and metal marker (sharpie, crayon etc. not pictured)
An angle grinder with a cutoff wheel is what we used to cut the tank. A metal blade on your sabre saw will also work if you are patient. We also used a wire wheel to clean the rust out of the tank, but this is optional.
Safety gear is essential when using an angle grinder. I can be rather cavalier with power tools, but I don't mess around with these things. A full face shield on top of the safety glasses is the official PPE (personal protection equipment) for this tool. A dust mask is also recommended if you are using a wire wheel on rusty metal.
A sabre saw (or jigsaw as some call it) Is what we used for the wooden base.
A drill and drill bits for the drainage holes (and also for possible work holding mounting holes)
A degreaser to prep the metal for paint.
Spray paint and clear coat for the finishing work.
Planting mix appropriate for your plants.
Step 2: Cut the Tank
Securely mount your tank. We used a vise to hold a metal protrusion, but anything that can hold the tank while you work is acceptable.
Mark the cutline on your tank using crayon, china marker, soapstone, sharpie, or other steel friendly marker.
Cut along the line with a cutoff wheel. BE CAREFUL! Angle grinders are as hazardous as they are useful. Pay attention to the rotation of the wheel and be sure that if your material flexes, it will flex AWAY from the wheel, rather than getting sucked into the wheel where it will cause the tool to kick. This is really important so I included a drawing to clarify.
Once you have cut all the way around you can pull the two halves apart. My expansion tank had a rubber diaphragm that required a bit of force to remove.
Those sunglasses are ANSI approved safety glasses, I should have had a face shield too.
Step 3: Refine Your Edge
The first cut was a bit crooked, so I placed the tank half on a flat table and traced around it with a small block to create a straight line. Then I recut along that line to clean up the appearance.
Step 4: Drill Drainage Holes
We used a cordless drill with a 1/4" bit (6mm) to make a series of drainage holes in the pot. The amount of drainage depends on the type of plant you have. We are planting succulents so we want to make sure water does not pool at the bottom. We put temporary bolts through these holes so we could mount the halves in the vise for the clean-up step.
Step 5: Clean Up Your New Pot.
We used a wire cup on the angle grinder to clean up the rust inside the tank. Then we wiped the whole thing down with acetone to prepare it for painting.
Step 6: Make the Base
We used a scrap of 2x4 lumber for the base. The length was eyeballed and the curve was traced from the tank itself. We used a jigsaw to cut out the shapes and a file to break the rough edges.
Step 7: Paint Your Pot
We used spray paint for the tank body and a clear spray urethane for the wood base. The pot will develop a rusty patina, which may or may not be desirable to you, if you do not paint it.
Step 8: Add Plants!
We sorted the plants by their preferences. If you are making an arrangement of different types, it is helpful to put plants that have similar water and sun needs together. If you buy succulents from a big-box store, it is recommended to remove as much of the original soil as possible.
Use a quality soil and give your plants a bit of room to grow.
Step 9: The Finished Product
We left the feet loose, but if you will be moving this pot around often then it would be a good idea to attach the base to the tank with screws or silicone adhesive. Enjoy!