Machinist
Here's a copy of the unfinished product if you want to see it in a coherent form: https://homebrewery.naturalcrit.com/share/ByUh8YqE4
The FFXIV's Machinist main in-game mechanic involves playing around with a "Heat" gauge while you shoot your gun and manage your ammunition, all the while aligning everything inside a window of time in which you use another ability called "Wildfire". You also get to occasionally use a flamethrower and a turret that you place and forget for the most part. I think I just described 90% of the job.
I just want to say that, first of all, the concept for this job as executed in FFXIV is not enough to make a D&D class out of. I know the Champion Fighter exists if we're arguing about class simplicity, but I don't think Machinist is supposed to be simple at all. I do feel that, if we explore Machinist's roots in the series, with the likes of FFVI Edgar's Tool ability, there could be enough to make a Machinist Class if done right; that is, if we look outside of the purview of FFXIV.
However, I didn't really have the time to make a whole new class, so I decided to opt for making a subclass instead. I initially thought about basing it off of Ranger and Rogue, but the Machinist neither casts spells nor does it make sense for it to have a Sneak Attack. Then I went to the Fighter class, and the more I thought about it, the more sense it made to me. I'm aware that there's an Artificer class Unearthed Arcana article coming really soon, and I will revise my work after it comes out, because it's likely that there could be some synergy with it.
Let's talk about using Fighter as the base class. When one thinks about Fighter, the first thing that comes to mind is a heavy armor warrior; However, that doesn't have to be the case. If the Fighter favors Dexterity over Strength (as a ranged combatant would), they don't meet the requirements for heavy armor. Additionally, the machination mechanic uses intelligence for it's abilities, both balancing it out and also forcing the Fighter to be more careful with their Ability Score Increase selection. It also doesn't hurt that the Fighter kit allows a Machinist to choose their fighting style; So you can build your own Hammer-wielding Machinist a la FFIV Cid if you choose to.
I considered the possibility of simply repurposing the Battle Master, but it didn't feel like it did the Machinist justice. When I thought about Edgar's abilities, I felt like the Machinist needed to have a repertoire of gadgets they could have at their disposal, perhaps mimicking the effects of some spells. That's when I turned to the Way of the Four Elements monk subclass, and realized that the general idea of what I had in mind had been done already, and I could take that as a model.
For the backbone of the subclass, I essentially took the Battle Master, and replaced the superiority dice mechanic with a specialized version of Ki Points. Battle Master's "Know Your Enemy" goes too well with some Machinist's Analyze ability.
I listed out all of Edgar's abilities (and I'm proud to say I was able to incorporate most or all of them somehow), as well as other Machinist-type abilities throughout the series. I noticed that both Battle Master and Way of the Four Elements subclasses had 16 or more abilities to choose from, and I tried to reach that number. Perhaps in the future, I can implement some sort of Bazooka and/or lazer gun, which I think are missing.
One thing I still have second thoughts about, is the fact that it took two pages to list out all the machinations, and that I had to basically repeat stuff that was already said in the spell that a machination was emulating. My reasoning is that machinations don't work like spells; they don't require the same components, and they can't be dispelled. Repeating effect descriptions also allowed me to tweak abilities for the purpose of balance.
All in all, this is a subclass I'll be dying to see in action. It encapsulates that over-the-top feeling you get when you play FFVI Edgar, and if you pick certain abilities (namely Flamethrower, Spiked Chain Cannon, Autoturret, Windblower, Debilitator, and Flash), you'll also be able to play like a FFXIV machinist. I might come back to it in the future, though maybe with the mind of turning it into it's own class.