Engineering is the opposite of entropy. It tries to create order, simple order that can be understood by human brains, so that we can build reliable systems that do useful things. Much of engineering is about making the physical structure (or software structure) of the system have a low entropy (low complexity, no tendancy to rust/degrade over time, statistically very high probability of being able to complete a cycle, etc).
When you build something, taking raw materials from their current state and assembling them into something like a car or rocket ship, is that the opposite of entropy?
not really. what you're doing is using an external energy source to locally order things at the expense of increasing global disorder (ultimately contributing to the heat death of the universe). some people will use a term https://en.wikipedia.org/wiki/Negentropy to refer to this process.