I have always wanted a dress or sweater with one of these adorable collars, but could never find one on anything in my size and to my taste. After looking up a few tutorials, it seemed pretty easy.. even easier when I figured I could use a detatchable collar I already own as a template!
Start with a collar, some fabric, a marker and optional trim and iron-on letters. (The great thing about this project is that you have a whole canvas there to do whatever you'd like with the message or image.)
Lay the fabric flat and trace around the collar leaving a couple inches allowance for stitching width.
I estimate everything here, drawing the collar flap beyond the original collar. Now you simply cut it out (you could fold it in half to check for symmetry) and trace an identical collar, cut that out so you have two pieces. Turn them right side in on each other.
If you want trim on the bottom, before you sew the pieces together lay trim in-between the pieces, seam closest to you, a few inches inside. Fold top flap back over and pin along trim's edge.
Sew around entire collar, skipping the dip in the "U" shape (where the back of the neck would sit). Turn inside out and push out corners and tips.
Hand stitch the hole in the neck and decorate!
Chibi Moon approved!