uncastable

adjective4

1. •
   That cannot be cast (filled with, or allocated, a theatrical role).

   • Colleen Dewhurst, though in many ways wrong for the virtually uncastable Josie, is as lucid and luminous […] — 1974
2. •
   That cannot be cast (converted to other data types).

   • They're strongly typed, uncastable pointers […] — 2000
3. •
   That cannot be set in a cast.

   • ...internal fixation in children with open, unstable, or otherwise uncastable forearm fractures […] — 2005
4. •
   That cannot be used for, or produced through, casting (manufacturing with a mould).

   • Casting must be done within a day or two of moulding or the moulds will begin to wind-dry and become uncastable […] — 1943