What I really want is an A3 e-ink display that is designed to have a pdf loaded onto it, then can be disconnected and taken around a machine shop. No WiFi or Bluetooth etc

You'll pay out the nose on that. From what I understand, the larger the e-ink screen is the harder it is to manufacture. Which is why small tablet ones reign supreme, and larger monitor sized ones are shockingly expensive, somebody else here has already linked to a 25 inch display for $1800