My budget has taken a series of hits in the last month – like car repairs of the "when we went to fix the X, we noticed that Y and Z needed replacing too" variety, and a hot-water heater that failed – so I'm going into hyper-cheapskate mode.
Before I glued my wallet shut, I'd been thinking that I needed some new pillowcases, because I'd already been in fairly-frugal mode, and mine were worn out. There are some things that I believe are worth the extra money for top quality, because the quality really makes a difference, and pillowcases are one of those things. A quick look on-line tells me I'd be looking at somewhere between $20 and sky-high for just one pair of pillowcases. Definitely not in the budget right now.
But it got me to thinking. I don't need fancy pillowcases, and I had this one fitted sheet that was really worn in the middle, right where I sleep, but was fine along the edges. Whaddya know – the unworn edges were just about the same width as a pillow case. I now have three "new" pillowcases, with the extra added benefit that the cotton has been broken in nicely (which is another reason why I hate to let go of a favorite pillowcase; they get so nice and soft after they've been washed a few dozen times). I saved twenty-to-infinity dollars, and I don't have to feel guilty about throwing stuff into the landfill.
If you want to make your own pillowcases, it's easy enough for a beginning sewer. It took me about an hour, total, to make three of them. All you need is an old sheet with about 2' of still-good fabric along each of the edges, a sewing machine that sews a straight stitch (nothing fancy required, but you can pretty up the cases if you have embroidery options on the machine), scissors, a few pins, a measuring tape and thread. Oh, and an iron. An iron can be your best friend when you're sewing cotton fabrics.
Short version of the instructions for advanced sewers (in this case, "advanced" just means you know what a French seam is, and have stitched one before): Cut or tear rectangles that are approximately 20-22" wide by 70" long. Fold in half, right sides OUT, to form a rectangle that's 20-22" wide by 35" long. Turn under the short ends by approximately 4 1/2", then turn the raw edge under an additional 1/2". Stitch these 4" sections down, about 1/8" to 1/4" away from turned-under raw edges, to from the opening of the pillowcase. Then sew French seams along each long edge to join and finish those edges. You can also use two pieces that are 20-22" wide by about 36" long, and simply add an extra French seam along one of the short edges.
Longer version for beginner sewers:
First, remove the elastic along the edges, and cut along the seam at the corner pockets, so the sheet will lie flat.
If you're not afraid to tear fabric, that's the easiest way to get straight edges for your pieces. Starting with the lengthwise edges of the sheet, tear a piece that's 20-22" wide, depending on what's still good on the sheet and the size of your pillow, by the length of the sheet. You should be able to get one piece that's approximately 70" in length from each long edge, and a shorter piece, at least 36" long, from each of the top and bottom edges. These sizes are approximate and generous. You can get away with narrower and shorter pieces, and a smaller turn-down at the pillowcase's opening, if you don't have enough fabric or want a tighter fit, or you can go larger for an over-sized pillow.
Take one of the long pieces, and fold it in half, with the right sides OUT and the wrong sides inside, touching each other. I know; it will look funny, if you've never done a French seam before, but do it anyway. Iron the bejeebers out of it, so it's nice and smooth, and all the edges are lined up neatly. Pin the side seams only about halfway from the folded edge up to what will be the opening of the pillowcase.
Turn under the raw edges at the opening of the pillowcase by 4 1/2" and iron them to create a nice crease along the pillowcase's opening edge. Fold the inner raw edge another 1/2", so the raw edge will be hidden inside the turn-under. Make sure the 1/2" turn-under lies flat, and the fold at the opening of the pillow is still flat and unwarped. This is the deep hem you'll see at the opening of a finished pillow case. Pin it in place, and stitch close to where the 1/2" is turned under (about 1/8" to 1/4" away from the edge). Do this for both of the edges of the pillowcase's opening. If you happen to have a fancy sewing machine with embroidery stitches, and you want to fancy up the pillow case, now is the time to do it, before the sides are stitched together.
Pin the remainder of the sides together, making sure that the edges at the pillowcase's opening are neatly aligned. Now we're going to do the French seams. If you want an overview, you can check out this tutorial. I usually skip the trimming step after the first seam, but if your seam allowance is uneven, trimming is a good idea.
Stitch both sides, with a 1/4" seam. Again, this will look funny to anyone who's used to making clothes with a 5/8" seam, but bear with me. And, yes, you should be making the seam with the RIGHT side of the fabric out, and the WRONG side inside.
Go back to your iron, and turn the pillowcase inside out. Iron the bejeebers out of those 1/4" seams you just made, so that all of the layers are pushed to one side of the seam (not opened, like you'd do for dressmaking), and then iron them flat, as if you were ironing the pillowcase in order to put it on the pillow, inside-out. Pin the seams in place, and stitch them again, this time approximately 1/2" from the edge. The end result is that the raw edges will be enclosed between the first 1/4" seam and the second 1/2" seam.
Turn them right side out, snip any stray bits of thread and iron the bejeebers out of them again, and you're done.
For the pieces that are half-size (20" x 36"), the procedure is the same, except that you'll also stitch the short end, opposite the pillow case's opening, the same way that you stitch the sides. In that case, pin (RIGHT sides out) and stitch two long edges and one short edge with a 1/4" seam, turn everything inside out, iron, and stitch all three edges with a 1/2" seam. You'll probably find that the corners aren't as neat as when you can simply fold one end of the pillowcase, but it's not really noticeable once the case is on the pillow.
As a final note, I don't recommend making your own pillowcases out of quilting fabric, or fabric you might find in a thrift store or at a flea market. It's not as high a thread count as the fabrics made specifically for sheets, so it's not as soft as you might expect, and if you could find a high enough thread count, it would be more expensive than simply buying good pillowcases. On the other hand, you can also make pillowcases out of top sheets that you aren't using, perhaps because the bottom sheet wore out first. You'll have to do the math to figure out how to maximize the available fabric, but you should be able to get three or four pillowcases out of a top sheet.