I said I would work on getting this together, hopefully it makes sense! The nap map ended up being too small and I'm just going to have to alter it to be closer to a crib sheet (lots of tutorials for that), but this would be helpful in trying to do calculations for smaller mats instead of a standard size mattress.
How to make your own Toddler Nap Mat fitted sheet
This will make a sheet to fit a nap mat with the dimensions: 24” x 48” x 2”, but you can adjust it to any size by adding 10.5" to the width and length, however, using the 10.5" addition will not allow you to adjust the depth.
- Fabric from store – 1 to 1 and 3/4 yards depending on the width (If the fabric width is 60” or wider, you will only need 1 yard. All others, you will need 1 ¾ yards. Your workable piece must be 34.5” x 58.5”)
- thrifted sheet, cut to a workable piece: 34.5” x 58.5”
- 1 package - ¼ inch braided elastic
- thread to match/contrast the fabric
- cardboard to make pattern, about 8 inches square
- Cut out your workable piece from your fabric. It should be 34.5” x 58.5”.
- Create a cardboard pattern to cut out.
- 1 - Square piece: 4.5” x 4.5”
- 2 – Right triangle: 1” x 2”
- See image below on how to arrange the 2 pieces to make the pattern.
- Use pattern to cut corners from your fabric. Your sheet should look like the multi-colored cutout. (Hint: Fold and press your workable piece into quarters and you will only need to cut the pattern once.)
- Sew French Seams to create the corners of the sheet
- Start in one corner of your fabric and fold wrong sides together, along the diagonal, matching where the pattern was cut.
- Using a straight stitch, sew a ¼” seam. Turn the corner inside out and press.
- Repeat on the remaining corners.
- Starting again, in one corner, this time, with right sides together, sew the same seam with a 3/8” seam. You should now have a French seam, and no raw edges. Repeat for the remaining corners.
- Finish the edges of your fitted sheet.
- Press a ¼” hem, fold over, press and sew.
- On the long sides, measure 11” from each corner and pin. You should have 4 pins, two on each long side.
- Set your sewing machine to zig zag, widest and longest stitch length. Anchor your elastic at one of the pins, with the tail toward the short sides. With an even pull, zig zag the elastic along the hem from one pin, across one short side and anchor at the next pin. Repeat on other side.
Here's the finished sheet. You're looking at the corners tucked into each other and the label I stuck on top.
So I've actually made 3 sheets in total, and I pulled the elastic by hand (like in my instructions) for two of them. For this pink sheet, I borrowed my mother-in-law's Elastic Wizard. This product is great! (I'm obviously not getting paid to say this since it looks like you can now only get this off eBay.) It comes with a foot that helps line up the elastic to the sewing needle, and little plastic attachments that feed and pull the elastic through depending on the width you're working with. It definitely helped maintain an even tension for the elastic and it helped get a zigzag right down the middle of a piece of stretched 1/4" elastic (which seriously becomes like 1/16")!