I plan on doing a set on the Ends of the Earth Sinister Six, and started with Mysterio. Not really a complex custom, but I wanted it so I could revert from EOE Mysterio to a somewhat classic Mysterio with cape as well. So here is the recipe:

Only figure used was the SPIDER-MAN CLASSICS MYSTERIO. 1)Cracked open the head, removed. Painted a pingpong blue and put in place. 2) Sculpted the neck-brace, painted Quinacridone Magenta (closest to cape). 3) Painted gaunlets and boots gold, but gloves the aforementioned magenta. 4) Removed the push pin at the back of the figure, filled hole with apoxie sculpt, painted. 5) Cut back of cape, repainted eyes.

Not the most unique Mysterio, but still a nice one for the purpose!