Extremely light weight, collapsable (yes... you read that correctly)
carbon fiber replication mirrors have been around for a while.

In his 2001 presentation at Stellafane, Dr. Peter Chen shared the
results of the technology at that time. He was then working on a 52"
primary that weighed in at 27 pounds. Up to 50 mirrors could be made
between cleanings of the precision mandrils:

http://www.astro-nut.com/stchen.html
Cheers,

Paul

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