McMaster-Carr catalogMcMaster-Carr actually has models of a lot of their fasteners, they aren't all perfect, and some take a little rebuilding, but it's a lot better than pulling out the Machinery's Handbook and starting from scratch. Find the part you want, then once you get to the part page (with the little drawing of the part) up top there is a download button, select IGES and it opens right up in Rhino! –Sam Page
Tyco Electronics catalogSimilar to McMaster-Carr: Find the part you want, then once you get to the part page, under the “Corporate P/N”, there will be a “CAD Geometry” link if they have the part in 3D, if that's the case, select IGES to download a zipped IGES file. - FREE always
Ultra 3D A range of high quality modern furniture models and accessories - FREE once you register.