The Craft of Scratchbuilding
Building Liverpool
Liverpool (Gauge O Guild Gazette)
Liverpool (LNWR Journal)
Building Clyde
Constructing bending rolls

Drawings and Information Sheets

Dividing head for the Sherline mill
Cutting spokes
Cutting flares
Bellows for Sherline mill. The original site seems to have disappeared, but these links should be enough information: cutting template and video. Added: Sherline now sell bellows

Traders (supplies)

ABC Gears - Suppliers of motors and gearboxes
Metalsmith - Nickel silver and other materials, also specialist tools
Laurie Griffin - An extensive range of quality castings
Scale Hardware - Miniature nuts, bolts, rivets, etc and threads down to 0.5 mm diameter
Grandt Line - Plastic moulded bolt heads, rivet heads, etc

Traders (tools)

Sherline - Machine tools, and lots of information about machining
Carter Tools - Mostly Taig products, but also the dividing head indexing plate
Cousins - Watchmaking tools and supplies, useful for small engineering
Hemingway Kits - Kits for lathe and mill accessories
Arc Euro Trade - Machine tools and metal working tools

Model Engineering

Lathes - Everything you ever wanted to know about machine tools, and then some
Home Workshop - A site for model engineering sales, wants, and information requests
Mini-Lathe and Mini-Mill - Two sites from the same author, about Chinese-made machine tools, but a wealth of information about tools and their use generally
Metal Web News - A large collection of articles about model engineering

Related Sites

Gauge O Guild
2.5 in Gauge
Gauge 3 Society
Historical Model Railway Society
National Railway Museum
Raymond Walley
- O Gauge model maker
Ian Rathbone - Model locomotive painting and lining
Maritima and Mechanika - Miniature workshop tools and accessories

Unrelated Sites (but I like them)

The Museum of Retro Technology
Craftsmanship Museum
Nick Baines   Model Engineering