Here's some great instructions from doityourself.com to take beloved t-shirts into pillows. The below instructions come straight from their site.
If you won’t wear those T-shirts again why not turn
them into throw pillows? A T-shirt with a nice design will make a lovely pillow sham. The best part is that some of the work is already done for you.
- Old T-shirt
- Sewing machine
- Taylors chalk
- Pillow or stuffing
Pick a T-Shirt
Choose a T-shirt that you want to use and check it for tears and stains. As long as the T-shirt is sound and clean, it can be used. You can create memories and talking points by choosing T-shirts with images or messages on them. If this is your first attempt you can practice on a plain T-shirt.
Check the Size
If the T-shirt is not a large size it is possible that you can use the body width as it is. If you are using an existing pillow to stuff the new sham then the size of that pillow will be taken into account.
Turn the T-Shirt Inside Out
With the T-shirt inside out check how much of it you will want to use to make your throw pillow. Mark lines to show where you want to cut the T-shirt. Make sure that you do not mark the lines through any images that you want to save.
Sew Along the Lines
The cutting lines you have marked will become the seams for your pillow sham. Sew along the one near the top of the T-shirt with a sewing machine taking care to keep the material flat. This isolates the head end so you can cut it off and make the material easier to handle.
Make the cut about ½ inch from the stitched line. If you have marked lines down the sides of the T-shirt, sew along those. Cut the surplus material away, again about ½ inch from the stitched line.
Fill the Sham
You have created a sham with one end open. Turn the sham the right way round by pulling the closed end through the open end. You should now see the images that you wanted to save nicely centered on the sham. You can place a pillow inside the sham or fill it with stuffing material.
Close the Open End
Turn the edges of the open in to the center by about ½ inch, more if possible. If you want to fit a zipper to make removing the sham easier, you can do that now. Remove the pillow or stuffing to make use of the sewing machine possible. Use a zipper that is closed and fixed at one end. Sew the zip in place so that the teeth are below the level of the fold. If you are not using a zipper, you will have to close the end with hand stitching.