Begin by laying out the fabric, cutting the flat sheet cleanly in half lengthwise. If you're using a flat sheet and want to add a personal touch, consider saving a template for extra appeal.
All my measurements will vary from yours, as mine are made directly to the size of the bedroom window, but this concept can be carried out to almost any size.
From top to bottom, I only needed 50" length for each window, and the bolt of black fabric darkened 54" wide, so I was essentially able to buy two yards of fabric (a total of $7.50!) and cut it to width to fit both windows. If I hadn't noticed this at the store, I would have brought home the fabric lengthwise (almost 4 yards) and there would have been plenty left over.
On top of that, I overlapped a yard of the blackout curtain (I had the store cut my two yards in two for convenience).
I used the miter saw to cut the 6 foot board in half; I calculated my curtains to be 36" wide, and each would require a header board that could support the weight of the curtain, and would easily attach to the wall. As shown on a curtain here, I used the electric staple gun to Attach both layers of fabric directly to the board.
I sewed plastic rings up and down both sides of the curtain and across the top under the wood header, spacing them about 15".
Use Stitch Witchery (the common 5/8" wide variety) to fuse the two fabrics together. Not shown but eluded in the image above, I also used the Stitch Witchery to seal a peg at the bottom of the curtain to give the Base a little weight and help it hang evenly..
Thread a thin but strong nylon rope through the rings.
The easiest and safest installation I did was to screw the wood header directly into the window frame, but I did this by hiding the screws under the layers of fabric so it would preserve its final appearance.
I added a small hook to the wall to anchor the weight of the curtain when it's lifted, and it's high enough that you won't worry if a child accidentally gets tangled up in it.
If you have a little slack in the center of the screen, you may want to add an extra row of plastic rings in the center of the screen to guide a third rope (I imagine if you're covering a window longer than 36 feet). "you'll want to be aware of this up front).
