Once I swapped the heads, I realized that Twoface's neck-peg is longer than the hole in the Batman's body.  I eventually had to attach the head with superglue.   I sanded the rough side of Twoface's head, and then used contour putty to broaden his jaw and to fluff his hair a bit.  After a while, I was unhappy with his mouth, so I filled it in completely with contour putty and re-carved it.  This turned out to be the most difficult part of this custom. 

The figure was painted with red, gold and flesh-colored acrylic paints.  Although some small lines on his wristbands and the outlining around his lightning were initially drawn with an ink pen, I had to go back over every one of them with a paintbrush... a very small paintbrush. 

Using Chris G's Scratchbuilder's recipe as a starting point,  the cape was made with Crayola Model Magic and gold elastic cording.   I rolled some Model Magic out with a rolling pin and cut out a cape shape.  Then, I cut out a separate collar shape.  Next, I lightly moistened the two pieces (moist Model Magic sticks better than dry), took a twist-tie, and sandwiched it in between the two pieces.  I had to put a little pressure on the pieces to make them stick together, but it worked. 

I twisted the tie together to hold the cape on his neck until it dried.  Before it completely dried, I shaped the cape into a more flowing pose, and then set him aside to finish drying.  Once dry, I trimmed off the twist-tie, sprayed the cape with my white primer, and painted the gold trim with acrylics.