As far as I can tell, you can only get a crystal option if you choose robotic arm 3 for torso.
1. I would love to see options for doing the same with the left arm and also being able to do both arms that way.
2. I would also love to be able to have my entire character covered in crystal.
3 come to think of it I would love to be able to have a robotic leg and a normal leg option for either leg.
I don't know how hard it would be for the dev team to do this, but it would be nice to have.
Thanks