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Here in the UK it is possible to buy long Perspex (=Plexiglass) tubes 
with 30cm diameter. I have successfully produced a high-vacuum 
exhibit using this material. Mine used only a short length of ~30cm 
tube, but a longer length should be equally resistant to external 
pressure. Be careful to avoid bending forces though. Even with thick 
walls, it is possible to see inside with perfect clarity because this 
material is very precisely formed and highly transparent.

There's a photo of my version here (scroll down to "Silence of 
space") http://www.interactives.co.uk/hands_rumbo.htm


[log in to unmask] * http://www.interactives.co.uk
*
Give people facts and you feed their minds for an hour.
Awaken curiosity and they feed their own minds for a lifetime.
*
Ian Russell 

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