A gun is very different from a medical device. The tolerances your automobile machinists are used to working at are much wider. Ventilators have to measure fractions of a cmH20 above ambient pressure, and they have to do so accurately to deliver gas, especially smaller boluses. I'm not saying it can't be done, I'm saying that training someone who is used to the tools used to building automobile engines will be practically unskilled at building ventilators, and you need to validate your people as well as your production processes, irrespective of whether you have blueprints for equipment. You have to validate everything or you will kill people with these new ventilators.