Disclosed herein is an efficient and cost-effective system for reconstituting bone pastes comprising a first syringe containing a reconstitution fluid and second syringe containing paste components, wherein said first and second syringes are communicatingly interconnectable. Also disclosed are novel methods for producing and storing bone pastes. Alternatively, a mixing syringe is disclosed, which is useful for reconstituting a paste, inter alia, comprising a flexible midportion, whereby repeated compression of the flexible midportion results in mixing the contents of the syringe.