Most electronics kits are available in both assembled and unassembled versions.  Model numbers that start with CK are unassembled and will require assembly which in most cases will require soldering.  UK model numbers are assembled versions.  All kits will require a project box if you are going to be using the circuit on a permanent basis and where indicated will require batteries or power source.  Please note that some of these kits can generate hazardous voltage levels and young children should be supervised when working with these kits.