Things you'll need:
-an old felted/shrunken wool sweater, or something for insulation
First, measure your FP. Add 2cm to the length. um...I didn't measure...what I did was use the one I made for J as a template...once you make one, most FPs should be the same around...We have a short one too, but all we do is flip down the top!
Cut the felted sweater to size.
Lay on chosen fabric.
Cut Fabric about 2 or 3 cm bigger than felt.
Pin both long and one short side, using felt as a guide (NOT pinning TO fabric)
Sew along the edge, the size of the felt, and trim off edges.
Flip right side out and slide the felt in. Tuck the cut ends in, and pin 3 loops of elastic inside.
Sew all around the edges, and 'quilt' the middle. This will keep the felt from moving around.
Sew 3 buttons on the nice side, opposite the loops.
Now you will have hot coffee for a little longer!