Making a homebrew class that interacts with weapon switching and i can't find the rules on drawing weapons to reference them.  So what are the rules?  I've always said to use a bonus action to switch weapons or to draw a weapon and no one has needed to correct on that assumption.  So i don't know if that's RAW.

By default you can draw or stow a weapon as part of your one free item interaction a turn and/or use your single Action to Use Item and draw or stow a weapon. It doesn't interact with your Bonus Action at all. There are Feats and a Fighting Style that can modify these rules, but those are the default rules that apply to everyone.

In addition you can drop a held item for free. So you could drop your bow, then draw out your sword in a turn and not waist your action.

A correction, a thief at level 3 gets to use "interact with an item" as s bonus action.

Also I believe there is a class or feat that lets you as part of the attack action draw and attack with a throwing weapon

Yep, as I said, I was just going over the rules that apply to everyone. There are class abilities, feats, and fighting styles that change the rules, but without those, what I said applies.

Examples of things that change this rule in some way: A Thief Rogues Fast Hands ability, the Dual Wielder Feat, and the Thrown Weapon Fighting style.

So to sum it up, RAW is to draw or stow 1 weapon for free on a turn. Anything past that you need to use "use an item" action. The exception are limited and far between.

Depending on what you are trying to do, it's your game and you can say whatever the rules are (the golden rule inside the DMG).

If you want inspiration for your homebrew class feature, not knowing what it is, I'd suggest something like the quickdraw feat from 3.5: roughly it says "you can draw or stow a weapon as a free action" and in 3.5 terms that meant any number of times in a turn.

I would like to draw attention to the "or" in "draw or stow". To switch weapons would require 2 turns, dropping a weapon, or the use an item action to complete.

One way to do this without messing with your action economy is to attack and stow one turn, then draw and attack the next. The only opportunity cost is reactions like opportunity attacks.

Dxjxc is right but if you are switching from two weapon fighting to something two handed it does not work.

Also note that donning or doffing a shield always requires an action

Quote from Jegpeg>>

Dxjxc is right but if you are switching from two weapon fighting to something two handed it does not work.

Also note that donning or doffing a shield always requires an action

 Also a good note.

If I were making a homebrew class based on weapon switching, I'd probably give them a feature that lets them draw a weapon as a part of the attack action. That way, each turn you could stow the weapon you're holding and draw a different one as you attack.

DxJxC's Post#6 describes what I understand as RAW quite well.

Anything beyond that requires DM input. As far as I know, there is no mention anywhere in the rules that says that picking up a weapon from the ground can be considered part of the attack. Dropping your weapon may be considered free (again, this isn't in the rules, but comes from a tweet, I think), but picking it up again might take an entire action or be considered part of the attack, depending on the DM. That, along with what happens to the weapon while it's on the ground, might make switching back to the first weapon tremendously more difficult than switching the first time.

Quote from scatterbraind >>

If I were making a homebrew class based on weapon switching, I'd probably give them a feature that lets them draw a weapon as a part of the attack action. That way, each turn you could stow the weapon you're holding and draw a different one as you attack.

 Drawing or stowing is part of the attack already, according to the object interaction rules - your free object interaction is the type of object interaction that is "while doing something else, such as when you draw your sword as part of an attack." Providing a feature that only allows one of those isn't doing what you think. The feature would have to allow the character to do both directly.

Quote from WolfOfTheBees >>

Quote from scatterbraind >>

If I were making a homebrew class based on weapon switching, I'd probably give them a feature that lets them draw a weapon as a part of the attack action. That way, each turn you could stow the weapon you're holding and draw a different one as you attack.

 Drawing or stowing is part of the attack already, according to the object interaction rules - your free object interaction is the type of object interaction that is "while doing something else, such as when you draw your sword as part of an attack." Providing a feature that only allows one of those isn't doing what you think. The feature would have to allow the character to do both directly.

 So is your stance that the Thrown Weapon Fighting feature does not work according to RAW? Because that's what I was modeling it from.

You can draw a weapon that has the thrown property as part of the attack you make with the weapon.

If a feature explicitly grants you a draw, then you don't have to use your object interaction to do it. So I'd give draw for free but still require object interaction for stow.

I’d argue that the feature allows you to draw a weapon after having used your one free object interaction to already do so, not that it allows you to do that *and* have an additional free object interaction. 

It's not giving you an "additional" one. It's not using it in the first place. Crossbow expert doesn't get around the loading property by giving you a bunch of extra actions to load your crossbow. It just removes the requirement.

To fit your interpretation, it would need to say "You can draw a weapon that has the thrown property as part of the attack you make with the weapon even if you have already used your interaction with an object this turn." Because you are applying a clause to it that is not there.

I didn’t say that it gave you an additional one, in fact I said the opposite. I said that if you have already used your free object interaction as part of drawing a thrown weapon, you can still draw another thrown weapon.