This is what our sofa looked like until yesterday. Well, the sofa looks exactly the same, but the cushions have changed:
Not at all goundbreaking (it's really just an envelope style cover) but a little bit different anyway. Now, before we get started can we just get over the fact that I so couldn't be bothered to iron the fabric for the back of the cushions? 'Coz I'm lazy like that. But of course, YOU should totally iron your fabric if you want to. But it's cool if you're lazy like me. Ahhh yeah.
Anyway, on with the show.
What you need: the cushions you want to cover. 3 pieces of fabric (1 for the front, 2 for the back) the size of your cushion for each cushion. You can use the same fabric for both front and back or do different ones like I have. Plus one piece of contrasting fabric which must be about 1/3 longer than the longest side of your cushion and about 10cm / 4" wide.
There aren't any exact measurements that I can give you, because it depends on the size of your cushion. You'll just have to wing it. That's what I did. Right now I'm just pretending that I know what I'm doing. I won't even mention that I had to adjust the size (was too big) of the cushions after sewing them and turning them right side out and putting them on the cushions... ;-)
Put one of your back fabrics on top of the front one. This is just so you have something to 'measure' the back against, you won't be doing anything with the front piece just yet. Fold over about 1/3 of the fabric and pin it.
Sew across it a few times, either with a matching or contrasting colour, whatever strikes your fancy. It doesn't have to be terribly neat either, it will be covered anyway.
Turn it over and cut off any excess fabric.
Place the back piece on top of the front piece again. Then place the other back piece on top of that and fold it at an angle. Not too steep an angle, though. And not from a corner either.
Cut off the small folded bit (if that makes sense..?) and measure the diagonal: this measurement + about 5 cm / 2" will be the length of your small piece of contrasting fabric.
Cut that piece of fabric and pin it to the diagonal edge. Sew the two pieces together. If you are using fabrics with right and wrong sides, please make sure that you sew right sides together...
Trim the seam and fold the contrasting fabric to where it almost meets the seam. Pin in place.
Stitch on top of the contrasting fabric. Use the same colour. Or a different one. But you might want to try and do as straight lines as you can to make it look all nice and neat.
Place the front fabric with right side facing, place the back piece with the contrasting edge on top with right side facing down.
Then place the other back piece on top of that. Again with right side facing down. Please note that the two edges must be towards opposite ends! Pin everything together and sew all the way around your fabric sandwich. Trim the seams and snip off the corners - without cutting the corner seam! Turn inside out (maybe a quick iron as well?) and place your cushion inside. Job done! Repeat for as many cushions as you need.
As you can see below, I used 3 different contrasting edgings that all go with the front fabric (I think so anyway!). This way there are LOADS of possibilities for mixing things up. I DO like multi-function!