1-1-1 build has many variations nowadays. The most common and popular one is
You're pumping marines as the gas for factory is coming up, building a factory while pumping marines.
At this point a 5 roach rush can occur, so you can build one tank, no siege mode + pumping marines.
Once you have the gas again to build a starport, make sure youre building a tech lab on your factory and just lift up and switch it with the starport and begin making banshee/viking depending on your hard counter/race.
This all depends on what you scout, if youre just doing a blind 1-1-1 it'll most likely fail unless you scout void rays or any rushes. After the scout just counter accordingly.
The weakest part of this build is factory to starport as protoss (4-gates) and zerg (baneling bust+more than 5 roaches) will do a lot of damage causing you to be on the defensive or lose.
1-1-1 you can do whatever you want, just remember if youre cutting SCVs youre playing an all-in game and probably dont plan to expand, but if youre forseeing a longer game continue to make scvs so you have enough to transfer to your natural.
Good luck and play around with different units for the 1-1-1 as what I have said is the most common build, you can even forgo the tank and get a hellion to harass and get banshee to follow up.
Scout, counter, win.
P.S A FRUIT DEALER SON