Just finished my first project of 2014. I made two 16" envelope pillowcases for my new sofa....when I finally go buy one in the near future. :-)
Instructions: (for 16" pillow form)
Cut one piece 17" x 17" for top/ front
Cut one piece 17" x 21" then cut this piece in half for back
Fold over one short edge of backs twice and press for finished edge. Sew along inside fold.
Lay top face up, place backs face down aligning edges and overlapping finished edges in the middle of the pillowcase.
Stitch around with a 1/4" seam allowance. I backstitched at corners and along finished edges to reinforce.
Clip four corners and turn right side out.
I will take step by step photos and update this post asap.