A car seat cover with elastic is great for cold or windy weather. I sell these at my etsy store (Itty Bitty Fashion) but if you want to make your own, I am happy to share the steps I took!
1. Cut top & bottom fabric 45 1/2" x 35 1/2"
2. Place the fabrics right sides together, place a cutting mat under each corner, take a paper plate, and cut the corners around the side of the paper plate.
Here's what the corners will look like after you cut. Stick a sewing pin in each corner to hold the two fabrics together.
3. Sew around the edge and leave a 5" opening. Seams are 1/4".
4. Cut slits into the corners (but not past where you've sewn). This allows the fabric to curve better when turned inside out.
5. Now turn the cover inside out and where your opening is start sewing 1"-1 1/2" from the edge. This is to create a pocket for your elastic so make sure it will be enough room for your elastic to thread through. Go all the way around.
5 1/2. Yes this is a half step :) I put my straps on after I did the elastic to make sure they were in the right spot, but I would suggest doing your straps at this point. See steps 10-13. Aren't you glad you can learn from my mistakes?!
6. Take your 1/2" or 3/4" elastic (I used 2 yards and then trimmed what was left) and put a safety pin through it.
7. Thread your elastic all the way around and pull it tight to your liking. I cut my elastic and ended up using about 4 feet total, just in case you're making this for someone else!
8. To connect the two ends of my elastic I used my serger. If you don't have a serger, overlap the two ends and sew through & back a couple of times to ensure it holds.
9. Now you can sew the opening. Fold in your fabrics so no raw edges are showing and make sure not to sew over the elastic.
10. Now for the straps. Fold them right sides together hot dog style (length wise). Sew around one short edge and along the long edge with a 1/4" seam.
11. Trim the corners.
12. Turn the straps inside out, fold the fabric in on the one edge you didn't sew, start there and sew around the edges with a 1/4" seam. Sew again over the short edge when you come back around to ensure a strong hold.
13. Place your straps on your carseat cover at 16" down and 12" across. I did a square with an X.