be cast in a mould
be cast in a (some kind of) mold
To be of a particular type (which is specified between "a" and "mold"). I hate the snow, but my kids just love it—they are definitely cast in a similar mold.
be cast in a — mouldbe of the type specified.
1991 Jean Bow Jane's Journey He was certainly not cast in a common mould. She had never met anyone like him before.