This stainless steel dummy source is 1" tall (1 1/2" including thread) and 5/8" in diameter. Although it has no markings on it, it was identified by Karl Haff as having been manufactured at Oak Ridge National Laboratory. At different times, Haff headed up ORNL's Source Safety Testing Program and their Radiochemical Processing Program. In fact, he used this dummy sources in classroom demonstrations at Oak Ridge National Laboratory.
It was milled from solid stock so that only one weld was necessary, for the threaded cap. The welding of the cap would have been tricky because it would have to be done at an angle—the thread would prevent the weld from being done from a perfectly vertical position. This would increase the risk that the weld had not completely penetrated the joint. The real version of this source would have contained approximately 1-2 curies of Co-60 or Ir-192. In some versions, Sr-90 covered with a thin window would have been used at the end of the capsule (a "thin window source"). In one case, a source was made using Kr-85 adsorbed to charcoal. One of their principle applications was in brachytherapy, e.g., the treatment of cervical cancer.
Karl Haff, personal communication.