Old Sears Paint Sprayer In-line Switch Question
I haven’t been able to find an in-line 125VAC 12A switch but there are 125VAC 12A switches which are a bit pricey  (at least what I consider pricey). On DigiKey.com you can search for switches. Here is one example: GTB-2B12 , 12A, 125VAC, https://www.digikey.com/product-detail/en/cw-industries/GTB-2B12/CW202-ND/3190599. Note that you’ll probably want to buy a project box to enclose the switch and wiring. There are project boxes on DigiKey.com as well.