These days, an engineer would probably use some sort of computer aided design (CAD) program. There are a number of them. They do a variety of calculations on demand.
Such software is typically fairly expensive. The more features and the smaller the industry, the more expensive it is likely to be. Plus, there may be special customization for the specific task, project, or device being designed.
The effort up front includes learning to use the software and creating the design in the software. You also need a fairly good computer to run it and use it. They typically require a butt load of RAM, hard disk space, CPU power, and you will want a large hi-rez monitor. Plus you probably want some largish printers for printing blueprints.
Once you have that, they can usually do a bunch of interesting useful things. For example, they can calculate the size, mass, etc., of the system. Depending on the program, they may give you help with designing the process of building the system. For example, there is the "ship in a bottle" problem. If something needs to go inside something else, you need to be sure there is a way to get it there. Depending on the type of thing being built, your CAD program may give you help with assembly sequence, bill-of-lading telling you what you need to order, and a bunch of other stuf.
They can also do things like creating blueprints for a variety of needs. Such as construction, maintenance, commissioning, deconstructin, and decommissioning.
The up-front cost is not trivial. But being able to do all that stuff from the basic design is hugely valuable. In my industry, I frequently have to look at blueprints that were hand drawn in the 1970s. And there have been several modifications of the system since it was built, with the blueprints not being updated. Or being updated by hand. With low-rez scans that look like somebody raised a family of parrots on it. If it was all in a CAD program, I could look at the new drawings, even look at the design history.
