Here's what you need:
A cheapo/uggo seat cover that you'd never wanna use in a million billion trillion years.
A sewing machine
Around 1.5 yards of 1/2 inch wide elastic
Something to copy your pattern onto (newspaper, carboard, posterboard)
Music (to have a mid car seat making dance party or just enjoyment.)
**For fabric, these are my suggestions:
For this use the fabric of your choice, but I will admit that for the seat part of your cover (where you sit and where you lean back) Cotton, twills and normal woven fabrics will work better. For the back and the underseat of your cover, you should use a knit or fitting it to your seat might be difficult.
You will need approximately 1.75 yards for the seat part. 1.75 yards for the back and underside of the seat, and 1.75 yards of the quilt batting for the comfort of your seat. (These are high estimates, you can probably get away with 1.5 yards, but you will have to squeeze it in tight.)
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Step 1: Find the Ugliest/cheapest Universal Carseat Cover.
So, you don't really need a seat cover to de-construct, you can look at my pattern pieces and copy them to some extent, but to make sure it fits great, you really should get a seat cover you can destroy first. I've been told you can get these at salvos (salvation army's) or other thrift stores.
**please note** You can also measure your own seat to make the covers specific to your own car. I still suggest making what I'd call a "princess" seam (because it helps the seat fit nicely. It also give a better, more finished appearance.
Step 2: Destroy!!!! Yipee!
Now you get to tear the ugly thing apart...well, maybe not literally. But go ahead, grab your scissors and/or seam ripper and get to cutting. The simplest way is going to be cutting along the seams, if you cut very close to the seams, the pattern will be more acurate. It will be most accurate if you just rip out the stitches...(BUT WHO REALLY WANTS TO DO THAT!?!?!) I did it the "easy" way, and just cut close to the seams.
Step 3: Make Yo' Pattern.
I labeled them like this.
Center Seat Back | Seat Back Side (cut 2)
Center Seat Bottom | Seat Bottom Side (cut 2)
**please note** These patterns are moved around a little to show the piece underneath that it belongs to.
Step 4: CUT IT OUT.
When cutting these patterns out, if you made sure it was a tight fit, give yourself a good half inch for a seam allowance (cause if you don't you'll be having some troubles.) Refer to the Fabric Cutting Chart for the what's what of your pattern.
Make sure you use some sort of quilt batting, interfacing or foam, it'll add some comfy cushh. I used a quilt batting, it was a pretty thick one, so it's gonna be mighty comfy.
Keep everything pinned to the pattern, it helps keep it organized, at least until you need to sew it.
Step 5: Sew What?!!
When sewing the seat, place the right sides together, with the batting/foam/interfacing on the outside. So you sew the right side of the seat bottom to the center seat bottom first, then you do the left (or whichever way you prefer, just make sure you're sewing seat bottom sides to the seat center.) This is where you would finish the seams if you want to be able to wash this safely. It will be more durable if you finish them in some way, serging, pinking or whatever you prefer. I serged mine.
Then you basically do the same thing, this time to the seat back center. You put the right sides together, with the batting/foam/interfacing on the outside, sew down the sides of the center, attaching the right and left sides. Once you have this done, sew the seat bottom to the seat back, matching up the seams, or aligning them in the center.
Step 6: But You're Not Done Yet!
You want to take the seat back and the long strip for underneath the seat and sew them together now. Line the bottom of the seat back with the shorter edge of the underseat, right sides together. Sew them together on both sides leaving it open in the center. This will look a little odd once it's done, but it works great, promise!
Step 7: Sewing the Back & Underseat to the Seat!
When you get to the seat bottom, you have to be careful, but you basically just pin around the edge of the seat (this is the long strip you just sewed onto the bottom of the seat back.
Once it's all pinned nice and neat, sew around the edge you just pinned, it is creating one solid piece.
Step 8: Elastic Casing (You're Almost There!)
At this point, I'm sure you'll run out of bobbin thread, because if you're like me, you always run out of thread whenever you're only a few minutes away of finishing something! Haha. So if you aren't out of thread, proceed!
Step 9: Finiiiiish!
To pull this through the casing, use a safety pin and guide it through, holding onto the end. Once you get to the other end, pin ends together and sew together neatly. Trim all threads, then let the elastic slide back into the casing, and sew the casing shut.
Woohoo. You're done!