How can you make a continuity tester?

you can take a siren from a home security device, not a speaker but a siren cause a siren works of voltage and a speaker works of wattage. take a battery that is capable of working the siren then just put the the siren in series with the battery and then take the two wires and put one on the open side of the battery and the other wire on the open side of the siren. If the siren goes off there is continuity between the two wires your testing if the siren dont then there is no continuity.... good luck..