The factory is a very important building but if this is your first time playing, you will want to know what a factory actually does. This building requires a lot of rare and expensive resources to build. You want to make sure you are actually going to use the building right?
A factory is used to produce items that require manufacturing. This includes plastic, circuit boards and fiberglass. All of these items are impossible to find through mining and all of the items it produces are required for a lot of the high tier gear and buildings.
A factory works much like a forge. Put items in, wait for it to finish and it will create the item for you. The ingredients required for a lot of these items are more rare and valuable. There isn’t much point in building this early on in the game. The building costs a lot of rare gems and you will need oil and other less common items to produce most of the stuff.
Is a factory worth it?
Yes, a factory is an essential building and you will not be able to create a lot of the high end gear and items if you do not have a factory setup. There is no rush to get a factory setup. Until you have items to craft that require the items that a factory produces, do not waste resources producing it. The effort wasted to produce it early will only slow you down considerably. Gems are much easier when you have a Quarry.