Originally Posted by M.I.Late
I have redone my chairs several times. I usually use a piece of foam rubber. The thickness is entirely your choice. You don't stuff the foam in - you build the fabric around it. If these are to be removable, you cut the foam to the chair size, cut the fabric bigger (enough to accomodate the foam rubber.) I top the foam with a piece of batting and then make the cover from there. There are probably several tuts if you just query making chair cushions... Hope this helps. Polyester filling will certainly break down, lump and move...
p.s. I get mine at Hobby Lobby because Joanns is way more expensive and Hobby Lobby has 40% off coupons regularly. Joanns does too, but theirs is twice the price of Hobby Lobby already.
This is also how I've made them(even though it's been awhile). I need to make some for my DM & this is how we'll be doing it! I'd suggest using the foam and covering with batting because your filling you're trying to use now WON'T withstand constant use. I'm sure you don't want to remake another set any time soon for your friend.