Google it and you may find a free pattern,otherwise the pattern books all carry them,ya know Mc Calls,Simplicity etc.
Kathi

If you watch your sales at Joann's, you might get the name brand patterns for a dollar or two.

It's been 22 years, but I remember making a baby seat cover for my oldest - we called it a "punkin seat". It wasn't a car seat...the ones we had (made by Coleman, I believe) had a nice cloth cover to begin with.

DonnaR/CA

Hobby Lobby here in Tx has Simplicity patterns for 99 cents this week.

I almost think it is just cheaper and easier to buy one from a company. There are A LOT of expensive ones, but I looked around and found some cheap ones. I ended up buying one from Luluboo. The one I got did not come with strap covers, so I made those myself, which was so easy to do. I made them in a cute but different fabric than that of the cover and it sort of personalized it a bit more. Here is the website:
http://www.luluboo.com

Here is a link that might be useful: luluboo

I`d suggest you start checking out the known car seat cover brands like Graco, Snuggle Mez, Babyloom etc.

Here is a link that might be useful: Best infant car seat cover