I know nothing about fabrication but as a graphic designer who does a lot of print work I can tell you that you will want to produce these graphics in Adobe Illustrator -- not Photoshop. Without getting in the weeds too much, you will have a much better outcome doing this as a vector graphic and not a rasterized image (JPG, PSD, etc.). Your Photoshop work will likely look like crap when it comes back from the printer.
My recommendation is to flatbed scan the faceplate using a large flatbed scanner, and then 'place' the image exactly proportionally onto an Illustrator file that has been correctly sized for print. Lock the image layer down, dim it to 50% opacity, and then create a new layer where you'll trace over the lines and text, before converting all text to outlines. Hide the lower layer and save as a PDF to send to your fabricator. It's a lengthy process but that's what the pros do.
FunkSoulLover is right about Helvetica Medium being the font of choice for these mixers.