ADS GmbH (www.ads-gmbh.ch)
W&F Mechanik AG (www.wf-mechanik.ch)
General CAD Forum (www.cad.de)
Database of standard parts (ww.web2cad.de)
Thread Info (www.gewinde-normen.de)
PennEngineering® press-in nuts, bolts, bushings, etc. (http://catalog.pemnet.com/category/all-categories)
Construction tips (www.konstruktionsatlas.de)
Conversion tables (www.hug-technik.com)