For this mod you will need:
Shapelock or similar low heat plastic (polymorph)
Spoon or other tool to modify
Warning: There has been some concern about having this material in close contact with skin either while cool or hot. Here is the MSDS for a similar product Friendly Plastic
. The MSDS does not suggest any ill results from contact with skin. It is true shapelock has not yet released an MSDS that is easy to find. If someone can find one, please comment below.
Of course with all hot things use caution and if doing this for someone who has low heat senstivities, use a glove or some insulator between the warm plastic and skin. The plastic doesn't stick you your skin very well, so when it dries, it comes right off.