I had a thought, assuming anybody looks at this thread. Take two levels in Artificer, the rest in Monk. By level two, you get the returning weapon infusion rom artificer. By Level 4, you get dedicated Weapon, assuming your DM allows it. You make a dart your returning weapon. You make the returning dart your dedicated weapon. Before you know it, I think you have a dart that deals a lot of damage. I'm still pretty new to theory crafting builds, so I need a little help figuring out how to get this build up and running.

Quote from Fack_Yu >>

I had a thought, assuming anybody looks at this thread. Take two levels in Artificer, the rest in Monk. By level two, you get the returning weapon infusion rom artificer. By Level 4, you get dedicated Weapon, assuming your DM allows it. You make a dart your returning weapon. You make the returning dart your dedicated weapon. Before you know it, I think you have a dart that deals a lot of damage. I'm still pretty new to theory crafting builds, so I need a little help figuring out how to get this build up and running.

 The biggest problem with this is that Monks need Dex, Wis, and Con - meaning it's hard for them to spare any INT for Artificer. 

There's also no benefit to choosing a dart over a javelin unless you grab the sharpshooter feat. 

Consider this. I could make int a dump stat, and just take take utility spells as the artificer. I could also start with my levels in monk?  Alternatively, I could scrap Artificer altogether and go kensei monk with Variant Human for the Fighting Initiate or Gunner feats. Any thoughts?

 Monk stat requirement is WIS and Artificer stat requirement is INT meaning you would have to have a minimum of 13 in both INT and WIS to both pick and multiclass into either of them.

Monk is a stat-heavy class, generally requiring a good amount each of Dex, Wis, and Con for their damage, AC, ability saves, and survivability. Having to sacrifice any of those for Int, at least on paper, doesn't seem to me to be worth it.

If you could get someone in your game to play an artificer and give you the Returning Weapon infusion, or if you can get your hands on a magic weapon with that feature, that's probably the best way to make this work. I think a thrown-weapon based monk could work as long as you stick with Finesse weapons and accept the loss of Flurry of Blows or Stunning Strike due to staying at range.

Quote from Llethander >>

 Monk stat requirement is WIS and Artificer stat requirement is INT meaning you would have to have a minimum of 13 in both INT and WIS to both pick and multiclass into either of them.

Monk is a stat-heavy class, generally requiring a good amount each of Dex, Wis, and Con for their damage, AC, ability saves, and survivability. Having to sacrifice any of those for Int, at least on paper, doesn't seem to me to be worth it.

If you could get someone in your game to play an artificer and give you the Returning Weapon infusion, or if you can get your hands on a magic weapon with that feature, that's probably the best way to make this work. Otherwise, I think a thrown-weapon based monk could work as long as you stick with Finesse weapons and accept the loss of Flurry of Blows or Stunning Strike due to staying at range.

 Monk requires dex and wisdom to be 13, just for clarity. 

There's no reason to stay with finesse weapons as long as you stay with simple weapons. All simple melee weapons that lack the heavy or two handed properties are monk weapons. As such martial arts gives you the ability to use dexterity instead of strength. You can use the javelin for its 1d6 damage and superior range (among thrown weapons) or the spear for its versatile property to allow you to wield it two handed in melee for the 1d8, while maintaining the ability to throw it.

As for the OP, you can pull this off with point buy. Put your 15 and 14 into wisdom and dexterity just like you would for standard array. Your 13 would go to intelligence or constitution with the 12 going to the other. "Sell" a point off your 10 to "buy" that point onto the 12, making it a 13. Your strength and charisma become your dump stats with a 9 & an 8 in some order. Then, you have all the intelligence that you need without affecting your monk stats much, assuming your stat OCD doesn't mind a few odd numbers among your stats. You'll still slow your progression with extra attack and ASIs, which is something to keep in mind. You could even have a returning thrown weapon (say the javelin) and a +1 melee weapon (the quarterstaff and spear offer the best damage, the spear can still be thrown), which would give you a decent boost in damage regardless of range. You'd have to determine if one of the lowest tier replicated items would be worth passing on (since armor and shield options are out for you personally due to monk) or if you wouldn't be better served using an infusion to help a party member. 

A Artificer/Monk multi for a throwing build is awkward because of the stats requirements and also because Flurry of Blows, one of the best Monk abilities, simply does not mesh very well with the throwing style you are trying to build.

Another big drawback is you cannot access the Archery and/or Thrown Weapon Fighting Styles without the investment of a feat or 2.  While strictly speaking you do not NEED them they greatly help the build.

In my personal opinion you are much better off going Fighter or Ranger (or even both) with the 2 levels in Artificer for a overall better thrower.  Both those classes give access to a Fighting Style, the Fighter gives Action Surge for more burst damage potential and more Extra Attacks at higher levels while the Ranger offers magic support for the party with spells like Goodberry and Pass Without Trace while also supplementing your damage with Hunter's Mark.

While the Ranger is just as stats intensive as the Monk I feel they offer a lot more which is why I rate them above the Monk for the thrower build.  The Fighter however fits in easy as pie needing only 13 STR or DEX (which you should easily have for armor purposes).

The real problem with this is it is fusing two things that WotC have been very stingy with - Monk and throwing weapons. Monk needs both DEX and WIS to be high, which means you give up a lot by delaying your ASIs or picking feats instead of pumping those stats. Multiclassed monks also suffer due to lower available ki, and of course it delays your Martial Arts progression which is kind of the reason you're there in the first place.

On the throwing side, you are right that the Returning Infusion is almost mandatory for a serious build. While the fighting style from Fighter or Ranger can solve the problem of making multiple attacks, they will still just be mundane darts unless your DM gifts you with a pile of magical ones (and if your DM is on board they could just give a full monk or fighter a single Returning Dart to solve that problem). Personally I think every magical throwing weapon should return to the user's hand because "magical", but that might not fly at your table.

I think ultimately a straight Fighter or Fighter/Artificer is going to be better for a dart build in the long run. As soon as you get that third attack you surpass anything Martial Arts would have given you. It doesn't have the same feel to it for sure, but throwing just requires a very specific path to stay competitive and it's really hard to fit on a monk.

The suggestions for a fighter build have merit, but if you are solid on the monk thrower, you'll want to go Kensei for the Kensei's shot and make sure that your melee weapon is the thrown weapon of choice.