- Wooden boards for the outside - cedar, cypress, or black locust are most advised for outdoor use as they are all very rot-resistant. I asked a cabinetmaking friend of mine what he thought of black locust, since it's all the rage in "green" circles, and he said it's good, but very hard to mill. In the end, our local place only had cypress or cedar anyway, and the cypress was very cheap (as it turned out, mainly because they were crappy boards), but seemed like a good bet.
- Plywood for the inside- We went with pressure treated plywood, since it will stand up best to the elements.
- Pressure-treated 2x2 - for the corners
- 1 1/2 inch, 14 gauge steel square tubing- for the structure. Oh by the way, you're going to have to know how to weld...
- Inch by 1/2 in steel channel - For holding up the seat boards.
- Decking screws - specially coated stainless steel screws to hold up to the elements.
- Plastic lining
- Rocks, dirt - to fill. I got my topsoil amended with leaf compost (50/50 mix) in bulk from a local place in Alexandria. $15 for half a cubic yard, which didn't quite fill up the whole planter.
- 115V flux core wire feed welder
- Abrasive cut off saw
- Chop Saw
- Cordless drill
- Vacuum - this wasn't technically used in the creation of the planters, but you're sure going to need it afterwards...