For the cushions I usually use balsa wood. It's really light weight and easy to cut.
First I covered the ends with a small piece of fabric and use a little extra bit of glue at the corners and pinch the corners closed.
Once the glue is dried I snip off the extra fabric.
Then I cut a piece of fabric roughly the right size to cover the rest of the cushion the press the edges under to the correct size. I found this awesome tiny iron at JoAnn Fabrics. I believe it's for pressing quilting seams. Of course I used a 40% off coupon.
I line up the fabric then glue just along the edges.
Here are the cushions on the chair base.
For this sofa, I used Carol's (Pepper from Mitchy Moo Miniatures) method of upholstering. She has a great tutorial.
For the legs, I usually use dowels or aluminum tubing. I was out of the right sized aluminum tubing so I used an aluminum channel from the hardware store.
Using a metal cutting bit on my little saw from Harbor Freight Tools, I cut small pieces from the aluminum channeling.
Then I filed the rough edges.
Then I glued the legs to the bottom using Quick Grip.