Now, some brilliant person has already created the concept of the "car seat strap cover," but what fun is buying some when you can make your own?
Here are my instructions on how to Make Your Own Car Seat Strap Covers
I apologize ahead of time for some of the photos...my camera battery died in the middle of production and I had to use my phone for the rest.
You will need:
fabric - I chose a soft "minky" fabric for the outside and a plain ol' boring cotton fabric for the inside.
Velcro
(optional) Batting or some other stuffing-type material (polyfil, cotton, scrap fabric, the neighbor's cat...)
1. Measure your car seat straps above the clip, length and width (IMPORTANT: be sure the clip is in the appropriate place your child wears it. You do not want the cover impeding the proper use of the car seat straps).My strap width was about 1.75" - I rounded this up to 2" (I call this the "Isabella factor" - gives me room to make a mistake with no real harm to the project) and added an extra inch to accommodate the Velcro.
On the length - I added only a 1/2" to accommodate the seams (no room for error on this one - yipe!)
No, I did not embroider some weird arrow motif on her seat belt. Those arrows indicate where to measure.
2. If your fabric has an obvious directionality (like this 
3. Cut out 2 pieces of the cover fabric and 2 pieces of the underside fabric.See that pizza cutter-looking thing? That's my new rotary cutter. *swoon*
4. Pin fabric, right sides together and sew, leaving an opening on one side (for turning).Who uses a white pin on white fabric? Really...
5. Clip the corners (it will make the corners less clumpy) and turn your fabric right side out.Now, onto velcro...
6a. Attach Velcro pieces to each of the long sides (on the underside fabric).To each his own when it comes to exactly how to attach the Velcro...if you've got a tried and true way to do it, then go for it. I personally did a basting stitch down the middle (red arrow) then went back and stitched around the outside (removing the basting afterward).
Note: I decided to put the Velcro in such a way so when closed it would be more like a clam-shell around the belt and not looped around to the underside of the belt. I didn't want unnecessary bulk under the belt, both for safety and comfort reasons.
Ah, my seam ripper. We have such a love-hate relationship, as you will see later on.
6b. Remember when I told you to do a scrap test for tension? Well, I didn't (do as I say, not as I do). It took three tries and a lot of hand cranking to get that (Behold! The Blur of Frustration!)
(Everyone, this is Betty. Betty - everyone)
6c. Don't get in a fight with your seam ripper. He will always win.Ow.
7. Originally, I decided against doing any kind of filling because the fabric was plush enough not to need it. However, I thought a thin layer of batting might make things a little more comfy for the slumbering child. So, this part is completely optional - especially if you are using a wonderfully soft, plush fabric for the outside.Note: I did not secure the batting to the project in any way. Yes, I realize the "afterthought" batting will eventually shift and clump after washing a few times. I can always open it up, replace it, and tack it down in some way. No biggie.
(Eeeew. My nails look gross. Gotta do something about that...)
8. Stitch the openings closed.
9. Hey look...the *grumble, grumble* Velcro works!
10. All done and ready to use!
