An apparatus and method for mixing a liquid component and a powdered component to form a bone filler has first and second syringes each having a barrel, a plunger and an exit port. The plunger is moveable with the barrel of each syringe along a longitudinal axis of the barrel. An end portion of each plunger extends beyond the end of each barrel when the plunger tip is spaced from the exit port and can be activated to move the plunger tip toward the exit port. A mechanism for mixing the liquid and powdered components is operatively connected to each of the barrels and plungers of the first and second syringes so that the relative sliding movement of first and second parts of the mechanism simultaneously moves the plungers and barrels of the first and second syringes relative to one another to move the combined liquid and powdered components back and forth between the first and second syringe.