I've only seen one CPI set for sale used ever, and could kick myself for not buying it. I'm still using my
original unit I bought new, but am starting to wonder if I should stockpile a spare gearmotor or a few spare electrical components just in case. I don't think concrete tubes would work very well for dev use,
though you might be able to impregnate them with liquid expoxy penetrant. ABS irrigation pipe would be
better. The original CPI drums were made of expensive noryl, which is a better insulating plastic per
temp control.