Yes, but my picture is of a small scale model. There is no real limit to the potential size. Construction cost is trivial.
The thing we saw did not change shape.
What I have read about and seen years later speaks about all types of cylinders, mostly at high altitudes, moving off at fantastic speed.
My dull and unremarkable 1200 foot long dark grey cylinder passed over me and my mother and dog for a very long time at an altitude that was roughly perhaps eight to ten storeys off the ground, yet in your face to see if there were any imperfection to suggest some type of human experiment going on in 1965. Even as a ten-year old kid, I wasn't that stupid.