text: Well thats really several questions.  Any fab shop with laser or plasma cutting equipment and some machine shop capablility can fabricate a centrifugal blower wheel.  We've build several using stainless steel.  But not with Air foil blades, which are only good for clean air, if any dust or dirt is in the air stream I'd recommend flat rather than air foil blades.\n\nAs for the second part, theres never been a time when it was easier to produce a high quality product without a lot of expensive tooling.  Advances in computer aided design and CNC machining have made it possible to produce precision parts in small quantities.  \n\nThe company where I work produces one of kind special machines and what components we can't buy off the shelf we can fabricate for in most cases ourselves.  But I could farm out all of the welding and machine work and only bolt the assemblies together will nothing but hand tools.\n\nOne of our competitors in Florida builds food processing equipment.  He farms out all of the components which require machining or welding.  He assembles his equipment with a wrench.  To do that would require accurate component drawings and proper tolerances.  Which if you have a good CAD system shouldn't be a problem.