Hi Stephan,
I've built a 16" Tridob, 10" 3-pole Highe and 22" UC.
All were carefully designed with CAD software and laser cut to make most bits.
Use the 10" from home in suburbia most because its so easy to put together and carry around fully setup.
16" gone to a new owner in dark skies. He leaves it setup and just rolls it out of the shed to observe.
Even with the lightweight Obsession UC style, I usually only use the 22" for all nighters at dark skies.
Building can be time consuming but very satisfying!
The most ATM scope designs can be found at:
http://stellafane.org/misc/links.html
Dobstuff makes kits based on the 3-pole Highe design
http://www.dobstuff.com/index.htm
Ultralight designs can be fraught with potential problems but the Highe design is well-proven and very "safe".