Years ago, (70s maybe) I came across an empty crystal oven. I know I have it in one of the storage containers of old stuff in my garage, but I can't find it. It was a proportional oven, but was otherwise an empty shell, so you could put your own circuitry inside (oscillator, voltage reference, etc.). Several small wires came out of it for power, temperature adjustment, e.g. Physical size was in the neighborhood of 1.5x1.5x3 inches. As I remember, it was manufactured by one of the major crystal manufacturers of the day (e.g., Knight, Bliley, etc.) Does anyone remember these ovens? I'd surely like to get my hands on a couple or three to play with. I search the net & Ebay occasionally for them, but so far, no hits. Dave M