Here's my shimmery silky watercolorish ikat pillow. It cost me a buck to make.
Like a lot of my pillow covers, it started out as a shirt. With my DIY batik pillow and my DIY no zipper shirt pillow, I tried to use existing seams or buttons to avoid work.
However, if that's not an option, you can still make a pillow pretty quick using my method below.
This pillow started out as a large thrift store shirt with poor construction but interesting fabric. The pillow form was a needlepoint thrift store pillow covered with tie dye fabric covered with batik fabric. Awhile back I gave up on zippers. If I want to change my cover, I just sew a new one right over top of the old one.
Step 1 above, cut two rectangles the approximate size of your pillow plus a few inches extra. Put the right sides of the fabric together. Sew two of the seams like an "L" shape as marked in the first photo.
Step 2 above, pull the fabric over your pillow form and pin fit the long seam.
Step 3, pull the fabric off the pillow. Sew along your pin seam, removing pins before you get to them. (Don't sew over the pins.)
Step 4, turn the cover right side out and slide onto your pillow. Fold the raw edges under and hand stitch the short seam closed.
Here's a tip: curve the corners a bit when pinning your seam. This keeps your pillow from having weird poked-out corners.
I had enough shirt fabric for a bed pillow.
And a chair pillow.
You can also make a pillow from a coat and from a skirt.