This 110" X 98" envelope will accommodate a king-size down comforter, giving it a little style and versatility--plus, it's easier to wash than the comforter! It's reversible: one side makes use of a unique fabric panel with wide borders, and the other side has a large central panel and narrower borders. It's all about measurements!
Step 1: Materials List:
1 graphic fabric panel, 45" X 56"
6 yards pinwale corduroy (45" w)
3 yards orange cotton (45" w)
9 yards white muslin (45"w)
double-sided iron-on hemming tape
Step 2: Measure Twice, Cut the Fabric, and Sew Borders
Sketch out the two sides of your pattern. Remember to add a half to five-eighths inch for seam allowances.
I'm going to call the orange bordered side Side A and the white bordered side Side B.
Because the center panels on my two sides had different internal measurements (that center panel), my orange borders (Side A) were narrower than my white ones (Side B). Side A is made of the corduroy and the orange cotton. I cut the corduroy into two 90" lengths and sewed them together along one side, forming a rectangle measuring 90" X 88". I cut the orange into four strips: two measured 7" X 90", and two measured 7" X 100". These measurements allow for seams. I sewed one 90" strip to the right side of the gray rectangle (right sides together, of course) and the other 90" strip to the left side of the gray rectangle. I sewed one 100" strip of the orange to the top of the orange/gray/orange piece and the other 100" strip of the orange to the bottom of the orange/gray/orange piece.
This formed Side A.
Side B, the panel and white border, has different measurements, because the internal panel is a single piece 45" X 56". I cut the white into 27" strips. Two were 56" long, and two were 100" long. I sewed the 56" strips to the outside edges of the graphic panel, and I sewed the 100" strips to the top and bottom of that central piece of white/panel/white.
Iron the seams toward the center piece (both sides of the comforter) and top stitch a half inch inside the center piece.
Step 3: Two Sides Together
With the right sides (A and B) together, sew along three edges, leaving one of the narrower (98") ends open. Clip the corners and turn the comforter cover right side out. Press the outer seams.
Step 4: Finish the Open Edge
Fold down the raw edges of the open end. Secure the edges with double-sided hemming tape. At this point, you have options as to how to close the end after you've put the comforter inside: Velcro closings, buttons, snaps, buttonholes with cord or ribbon running along width of the cover. I used Velcro dots.
Step 5: Put the Comforter Inside
This can be tricky, but it's just fabric, so you're probably not going to break it. Stuff the corners of the comforter into the corners of the cover and work it in from there. Secure the open end with the Velcro (or buttons, or whatever you used), put it on a bed, and smooth it out.
Step 6: Tips and Hints
First of all, EVERYTHING hinges on your measurements. The good part is that, because the comforter itself is so flexible, if you get your seams straight, a half inch won't make too much difference. But you don't want to acknowledge that fact until the end. If you start with a bad measurement, you'll only lose dimension as you go along.
Yes, you could do this with a single gigantic sheet. Well, two gigantic sheets. A California King will accommodate the dimensions for a King-size comforter.
Brace yourself: This is a LOT of fabric to work with. But it's just a matter of straight seams. If you're working with a great design or with colors you love, you'll see the project through.