Step 1: Pick Out and Wash Your Fabric
2 Yards Flannel
Roughly 80" of 1/4" wide braided elastic
Head to your favorite fabric store and purchase flannel in 2 yard increments. The fleece should be as close to 45" wide as possible. Flannel is generally a couple inches shorter because of how it is made. I purchased 4 types because I wanted to make 4 sheets. Also purchase 1/4" braided elastic. I bought 8 yards. If you can you want to get as close to 80 inches per sheet...since I'm being frugal I just cut 8 yards into 4, but if you're buying by the inch, get 80 inches for each sheet you want to make.
Try to hit a sale, fleece can be 5 or 6 dollars a yard but I got this particular fleece for $2.50 on sale. Since A crib sheet is about $15-$20 for a cute design, you want to try to keep your costs down to make it worth your effort...that is if you're trying to save $. If you're just trying to make cool sheets that go with your particular decor, go wild :)
Wash and dry the flannel. This is VERY important. You don't want to go through all this effort and have your sheet shrink after you make it!
Step 2: Fold, Measure and Cut
Generally when you sew you cut off the selvage edge, that's the edge where there's generally writing, or it's white. I left mine on because when we fold up the edge you won't see it and since flannel is not 45" you need all the extra surface you can get.
Fold your fabric in half and then half again so all of the corners of the fabric are together.
Measure 8 inches in each direction from the corner and mark with a pin. This creates a square in the corner.
Cut out the square and you have now cut out all 4 corners at the same time.
You could optionally measure this out 4 times and cut out each corner, but this works really well as long as you have folded your fabric neatly.
Make sure to save your corners, these are going to be used for the burp rags later.
Step 3: Pin, Sew and Zig Zag the Corners.
Straight stitch it and then go over the very edges with zig zag. This will help keep the corners from fraying when you wash.
This makes the corners of your fitted sheets.
Step 4: Zig Zag or Serge the Rest of the Sheet
Step 5: Pin and Sew Around the Edges
Make sure to leave a 3 or 4 inch gap at the end so you can thread the elastic in. It's easiest if you start in the middle of one of the sides of the sheets, versus a corner.
Step 6: Insert Elastic and Sew
This will be hard to go around the corners, which is why I noted to make your hem larger than 1/2 inch, so that the resulting hem has a 1/2 inch space.
Once you have gone all way through, overlap the elastic and zig zag it.
Then pull the elastic into the hem and finish the hem edge.
Voila! A fitted Crib Sheet!
Step 7: Burp Rag
Place the "right" sides of the fabric together.
Starting on one side (not a corner), start a straight stitch, go almost all the way around the square, leaving about 3 inches.
Turn it inside out.
Then do a straight stitch all the way around the piece, this will finish off the hole you left and make a nice edging.
Done! You'll have enough to make two and you won't have any scraps left over!