A dosage size multi-chambered, container having separate sealed compartments is provided and includes constituent materials for forming a wallboard joint compound. The container includes a first compartment containing a first mixture including calcined gypsum, a set preventer and water, and a second compartment sealed from the first compartment with a seal and containing a second mixture including a set initiator and water, wherein upon breaking of the seal, the first and second mixtures are combinable by kneading action to provide a dose of the wallboard joint compound.