The 50mm objectives of a vintage 7x50 binocular were replaced with 90mm objectives. This resulted in an 18x90 binocular.
The converted binocular makes use of off the shelf threaded photographic camera rings, eliminating the need to machine metal components.
A pictorial record of this project was made and can be shared on:

http://www.scribd.com/doc/10315218/Binocular-Rebuild-2

Prior to construction the vintage binocular was disassembled, for cleaning, and a this pictorial record is shared on:

http://www.scribd.com/doc/11912773/Binocular-Disassembly1