Portals

Fabricating.com --- (Website has displayed a placeholder for some time; they may be offline.)

Fasteners Clearing House Sourcing Network --- Search for parts manufacturers and distributors currently have in stock.

Industrial Fasteners Institute — Manufacturer Search

MatWeb — Material propery data

Octopart — Search engine for electronic parts

ThomasNet(r) — Product sourcing and supplier discovery platform

TraceParts — A huge choice of 2D & 3D CAD files, models and drawings.

Trace Parts Online — Free 2D & 3D CAD files, models and drawings of mechanical, electrical & mechatronics part catalogs

TSF Global Fastenting Solutions — (Spain)

Zycon — Industrial directory, engineering resource, and vertical search engine