I figure this can become a general resource, though I'll start it off with a specific question. I am interested in buying some cylindrical rotary files, based on a recent discussion of notching tubing for fuselage work. I have checked what I consider to be the Usual Sources: Aircraft-specific stores: Aircraft Spruce (aircraft tools, materials, supplies): http://aircraftspruce.com/ The Yard Store (many specialty aircraft/sheet metal tools, some surplus): http://yardstore.com/ Wicks Aircraft (similar to Aircraft Spruce): http://wicksaircraft.com/ Industrial suppliers: MSC Direct (industrial tooling and supplies): http://mscdirect.com/ Little Machine Shop (machine tools for the Home Shop Machinist): http://littlemachineshop.com/ Grizzly (imported machine tools, upscale-ish version of Harbor Freight): http://grizzly.com/ Northern Tool and Equipment (similar to Grizzly): http://northerntool.com/ McMaster-Carr (industrial supplies and equipment, most expensive, biggest selection): http://mcmaster.com/ Consumer suppliers: Ebay (what don't they have?): http://ebay.com/ Amazon (purveyors of all things consumer-oriented): http://amazon.com/ Harbor Freight (cheap import junk with the occasional gem): http://harborfreight.com/ In compiling this list I did finally find sources for everything I want (a set of about 5 sizes of cylindrical rotary files between 1/4" and 1"), with a few cheap ones at The Yard, and the remainder at McMaster-Carr for dear-lord amounts of money. However, I know there are other sources of tools and equipment out there, which I've forgotten, or just don't know about. Where else should I be looking? What little aviation tool supplier do you know about, that you're always recommending to other builders? Let's make this a master list of places to go when you need to find that special tool for building an airplane.