Old Products as IP

Your legacy products can function as a kind of intellectual property portfolio. If you are ever sued for patent infringement, you may be able to invalidate the intellectual property you are accused of infringing by showing that you were practicing the invention before your accuser filed for patent protection.

To build an IP portfolio of legacy products, simply archive CAD files, specifications, marketing material, source code, and production images.  Also note when each product was announced and sold.  It is a good practice anyone, and if you become involved in patent litigation, may be invaluable.