Is there a word to describe a general class of objects which are specifically designed to hold the form or shape of another object.
Almost the opposite or inverse of a mould. In a similar way that a skeleton holds the shape of a body, or a cobbler's iron holds the shape of a shoe while being worked upon.
I'm thinking of something in a similar vein to a brace, frame, scaffold, or a jig. Specifically a solid object inside of another object that would not hold its form otherwise.
The context in which I wish to use this word:
"The coil is wound and bound tightly to the plastic
word, in order that the coil maintains it shape and form"