Hi Paul,

to IIS, mate!
At what stage of your scope are you at? If at the planning stage, the design selection process is less complicated, not easier though.
There are many web sites that have links to designing all aspects of a scope. The spider and secondary for me is a little illusive for me too unless you have a pretty well decked out metal work shop.
Having said that, the following site is good:
http://stellafane.org/misc/links.html
You can also do a search for big dob and newtonian sites and see what solutions they've come up with.
Mental.