Every year, Americans go wild for Christmas. It starts right after Halloween, as the radio stations switch to carols and classics, and then turns into a shopping frenzy the day after Thanksgiving. According to the U.S. census, it also includes cutting down about 17 million live trees for living room displays. These trees often end up in the landfill, or, at best, mulched. From a sustainability perspective, this process is largely carbon-neutral, as the trees emit no more carbon dioxide as they rot than they absorbed while growing. But that fails to account for all the petrochemicals used to plant, fertilize, prune, cut, deliver, and dispose of said trees. Artificial trees aren't much better; they are often made of PVC, stabilized with lead, and are neither biodegradable nor recyclable.

This year, make a more sustainable choice: a flat-pack, lightweight, wood tree made from scrap plywood. It can be made in any size, takes up no space to store, is cheap, reusable, non-toxic, with a sleek, modern aesthetic.

This whole project, from sketch to set-up in the living room, took me about three hours and cost me nothing (assuming you can scavenge some plywood). It requires no fasteners or specialized equipment. I made mine from OSB since it was what was lying around the shop, and the random flakes make for a nice bark-ish texture, but any sort of plywood will do.

Merry flat-pack Christmas! And, if you're in a giving kind of mood, throw a vote my way in the Instructables Design Contest . . . !

You will need these materials:

2 pieces of 3/4" plywood, OSB, or other sheet goods, approx. 16" x 24"
Christmas lights
Tung oil or finish of your choice

You will need these tools:

Circular saw
Jig saw or handsaw for inside corners
Sander
Drill with 1/4" and 3/4" bits
Router (optional)
Ruler
Tape measure
Pencil
Rags
Safety glasses, gloves, etc.

Step 1: Layin' Out

The tree I made is 24" tall (to the base of the star) and 16" wide at the base. You could make it up to about 48", I think before it would become too wobbly. Try and stick to a base width that is about 2/3 of the height, which gives a graceful proportion to the triangle.

Start by using a circular saw to rip the plywood down to 16" wide. Strike a line at 24" up from one end, marking a centerline. Measure 2" off each side of the centerline. Connect the corners of the base with those two marks. Carry the lines through until they intersect, which will form the point of the star.

Lay out a trunk and a base; I made the base about 2-1/2" wide, and the tree trunk about 5" wide. Mark out a star, angel, or other design at the top of the triangle.

Measure and strike a vertical centerline, then measure 3/8" to each side of it and strike two more lines. This will be the notch in each piece that allows them to interlock.

Step 2: Cuts

Using a circular saw and all proper safety equipment, cut out your tree halves. For all the tight inside corners and other intricate parts, use a jigsaw or handsaw.

Drill a hole at the center of the eventual notches that will hold the halves together, then run the saw up to meet the hole. Take special care with these cuts: they should be straight, and cut slightly to the inside of the lines for a tight fit. Also be sure that they mirror one another, one coming from the top to the center, and the other coming from the bottom to the center.

Once cut out, clamp the two pieces together and mark a series of notches along the slanted outside edges. I spaced mine 2-1/2" apart, 3/4" deep. At the inside end of each notch, drill a 1/4" hole, then make two cuts to meet the hole with the jig saw. I found a 1/4" fit the Christmas light wire fairly tightly, but you may want to experiment on a scrap piece to make sure your notches hold the lights securely.

Step 3: Finishin'

At this point, you can notch your tree together, slap some lights on it, and call it done. However, I took an extra minute or two to run over all of the edges with a router and a roundover bit, as the OSB tends to be flaky and splintery on the edges. Next, I sanded it thoroughly with 100-grit sandpaper and hit it with a coat of tung oil. Any sort of polyurethane or stain will help it last for years to come.

To assemble, slide the slots together, then thread Christmas lights in a spiral from the top to the bottom, hooking the wire into each notch. You could hang ornaments from the wire, or drill additional holes in the structure.