A machine suitable for mixing first and second foam precursors to produce foam within a bag, the machine being adapted to perform a method according to claim 15 and comprising: a base (14; 214; 314) and a shell (12; 212; 312) moveable relative each other between: (i) a base/shell disengaged position, in which the base and shell are spaced apart to permit insertion of the bag (100; 400) between the base and shell, and (ii) a base/shell engaged position in which the shell and base press together to hold the bag between the base and shell and to divide the bag into (I.) a mixing chamber (120; 320) and (II.) a remainder portion (122; 322) so that the mixing chamber is isolated from the remainder portion of the bag; a first nozzle (58; 358) adapted to inject the first foam precursor into the mixing chamber within the bag; a second nozzle (60; 360) adapted to inject the second foam precursor into the mixing chamber within the bag; and a mixer (43, 45; 370) adapted to engage the mixing chamber of the bag to provide mixing energy to the first and second foam precursors within the mixing chamber of the bag when the base and shell are in the base/shell engaged position, thereby facilitating the foam reaction between the first and second foam precursors; wherein the shell comprises a bottom jaw such that when the base and shell are in the base/shell engaged position, the bottom jaw is adapted to press together with the base to hold the bag between the base and bottom jaw to divide the bag into the mixing chamber and the remainder portion. a base (14; 214; 314) and a shell (12; 212; 312) moveable relative each other between: (i) a base/shell disengaged position, in which the base and shell are spaced apart to permit insertion of the bag (100; 400) between the base and shell, and (ii) a base/shell engaged position in which the shell and base press together to hold the bag between the base and shell and to divide the bag into (I.) a mixing chamber (120; 320) and (II.) a remainder portion (122; 322) so that the mixing chamber is isolated from the remainder portion of the bag; (i) a base/shell disengaged position, in which the base and shell are spaced apart to permit insertion of the bag (100; 400) between the base and shell, and (ii) a base/shell engaged position in which the shell and base press together to hold the bag between the base and shell and to divide the bag into (I.) a mixing chamber (120; 320) and (II.) a remainder portion (122; 322) so that the mixing chamber is isolated from the remainder portion of the bag; a first nozzle (58; 358) adapted to inject the first foam precursor into the mixing chamber within the bag; a second nozzle (60; 360) adapted to inject the second foam precursor into the mixing chamber within the bag; and a mixer (43, 45; 370) adapted to engage the mixing chamber of the bag to provide mixing energy to the first and second foam precursors within the mixing chamber of the bag when the base and shell are in the base/shell engaged position, thereby facilitating the foam reaction between the first and second foam precursors; wherein the shell comprises a bottom jaw such that when the base and shell are in the base/shell engaged position, the bottom jaw is adapted to press together with the base to hold the bag between the base and bottom jaw to divide the bag into the mixing chamber and the remainder portion.