G'day Waxing-Gibbous,

mate to IIS.
'Twigs & mucus' is used to reduce the cost of making in expensive scopes. Unfortunately, both scope buyers & manufactures can see dobs as the poor cousin of telescopes. This can also mean that alot of people end up striping the optics out of their shop bought scope & making thier own scope, or making significant modifications to the scope. Both instantly kill their warranty.
If you are after a seriously good dob, with a few bucks in your pocket, have a look at SDM scopes. They are an Aussie crew who have really, really impressed everyone. I had a look through Norm's 14.5" SDM. Oh-Boy! Sweet as!
http://www.sdmtelescopes.com.au/SDM026.html
SpaceZebra has found new love with 'Albert':
http://www.sdmtelescopes.com.au/SDM013.html
In so far as wood is concerned, plywood is lightweight & strong, can be made moisture resistant, easy to work with, and the grain can look beautiful with a lick of varnish. All aluminium is also used, particularlly in making ultra-light scopes, similar to SDM013. It is just that tooling up for it is expensive, & an all aluminium frame is more expensive, just from the raw material.
CF is used in some big scopes too, especially the poles:
http://synrgistic.com/astro/24inch.htm
Both ends of this scope are all aluminium. I'm sure we
all would like a scope like this, few of us could make one, let lone afford one. Damn beautiful, aint it!
Also note, that regardless of the materials used in a dob, you will be 'maintaining the deck', the deck being collimation. No one gets away from that. But that becomes second nature eventually, & only takes a moment or two on setting up.
The only grease & oil change that is then required is occassionally cleaning the bearing surfaces. Again, no one escapes that one.
If you are really keen on the engineering aspect of dobs, borrow or get a copy of 'The dobsonian telescope' by Kriege & Berry. Even if you don't make your own, the info in it will help you make informed decisions on any future dob you may buy.
Mental