Are there any abilities, features, or magic items that can increase gold gain, or multiply currency in a permanent way?

Question

I have an idea for an avaricious (but not evil) busker bard character, whose motivation to obtain money is similar in magnitude to Scrooge McDuck (complete with Swimming Pool of Coins stretch goal). The character is intended as a wholesome goof, which means: not murdering, not stealing, and not profiting from illicit activities.

Another note of inspiration is the Bard class from For the King, who obtains lutes which add small percentage multipliers to gold gained in combat.

The problem is that I can't seem to find any items or abilities that modify the gold you gain in the course of adventuring, nor ones that multiply existing coins. I understand that there are serious balance concerns with such abilities (especially in low and mid tiers of play), so I'm not exactly surprised. But, one holds out hope.

Does anything like this exist in low or mid tiers of play (lv. 1-15)? I've seen the following, and rejected them:

College of Creation

The abilities are limited to "AN" item, so there is a small aesthetic conflict on two fronts: the created objects could only be single coins or gems, and also they disappear after a period.

Simulacrum

Items are not duplicated.

Fabricate

Dubious whether a DM would allow coins to be smelted into solid gold for profit.

Answer 1

As has been said, D&D treasure is tied to the game world--so a "+5% gold looted" mechanic isn't something that exists. Either the coins are there, or they aren't.

That said, there are a number of magic items in D&D 5E that create things of value at little to no cost. These can be leveraged by a traveling character to make money from nothing but the magic item they have acquired. This, of course, always assumes you can find a market for what stuff you've created.

Alchemy Jug

This magic item can, once per day, produce certain amounts of liquids. For the sake of legality and maximum profit, I recommend using it to produce acid. The jug produces 8oz of acid. A vial holds 4oz, and a vial of acid is worth 25gp. So, your alchemy jug can conjure 48gp worth of acid daily (a vial costs 1gp).

Cauldron of Plenty

Thrice per day, this cauldron can turn 30 gallons of water into a hearty stew sufficient to feed 120 people. This stew could be presumed to count as, at least, a 'Modest' meal which, according to the Food, Drink, and Lodging table in the PHB is worth 3 silver pieces. Theoretically, assuming you can sell out your stew, this means that every day you can convert 90 gallons of water (basically free, assuming access to a body of water or good well) into 36gp.

Decanter of Endless Water

Not hugely profitable in most situations, but can ensure you always have water for your Cauldron of Plenty. This could turn properly profitable if you're in a desert or other locations where water is scarce and you can sell.

Marvelous Pigments

These are, alas, consumable--but a single pot of this allows you to cover 1,000 square feet of a surface, and you may 'paint' objects worth up to 25gp that are permanently created. And, importantly, you don't have to be a good artist to use them--they magically flow into the form you are concentrating on.

So, I suggest finding a gemstone worth 25gp and 'painting' copies of it. Or, perhaps, 25gp art objects. It'd be terribly hard to figure out exactly how much money you could make in this way, because it depends on how big the thing you're painting is...but this 1,000 square feet of 25gp gems would likely be a large number of gems. Or if you wanted to go straight to gold...

Just to use Waterdeep as an example, Waterdeep: Dragon Heist tells us that a copper Nib is about the size of a thumbnail, and a gold dragon is about 50% bigger than a Nib. According to this, we can estimate that a typical human thumbnail is about 0.35 square inches--so we can estimate that a Gold Dragon is about half a square inch. 1 Square foot is 144 square inches or 288 gold dragons, so we can ballpark that one pot of paint could produce something like 288,000 actual gold pieces.

Caution: this is certainly counterfeiting...but gold coins are worth their own weight, so just making little squares of gold the size of a gold dragon would be legal.

(Wow, I went deeper on that rabbit hole than I meant to)

Non-magic item means

Gambling

As is laid out in this answer, gambling is a fantastic way to make lots of money. You're a Bard, you have a high Cha (which covers 2/3 checks for gambling), lots of skills, and you have access to Expertise. If you can manage to get your bonus in at least 2 of those skills up to a +16, that downtime activity just prints money as long as your DM will let you get away with it.

Spellcasting Services

You're a Bard, you have access to some pretty helpful spells. When hanging out somewhere and figuring you won't need spell slots, offer your services. Note that the official rule for "how much is spellcasting worth" is "No established pay rates exist"

Answer 2

Ability Checks

D&D is not a video game; the rewards you get for adventuring are tied to the game world, so it would not make sense for a feature to merely grant more loot or gold outright.

Instead, you want to negotiate with the game world to get more out of your adventuring time. This is represented by ability checks, of which multiple skills can benefit your endeavor to gain more wealth from adventuring. Here are some key ones (ignoring illicit options):

• Investigation can be used to locate hidden treasure caches, especially in dungeons and other monster lairs.
• Perception and Insight can be used to notice opportunities to gain more wealth.
• Persuasion can be used to negotiate better awards for quests, or better prices for recovered loot.

Just remember, that the capacity and effectiveness of these efforts are entirely DM dependent as the DM asks for ability checks when they are necessary and sets their DCs.

If you are interested in using skills to help in gaining wealth, I recommend explaining this to the DM so they can work with you and offer more opportunities to leverage that aspect of your character.

Downtime

Another way to amass wealth outside of adventuring is Downtime. Especially with the rules in Xanathar's Guide to Everything, a number of downtime options can yield fairly reasonable profits. These are:

• crafting and selling magic items (can be very profitable with the right renewable source of items)
• gambling
• pit fighting
• work

If you are interested in gaining wealth during downtime, be sure to train your character in relevant skills, but be wary of other in world consequences of the downtime (including complications when using the Xanathar's rules).

I've done an analysis of the most profitable options in this Q&A, although the complications are something to consider beyond just the money.

Answer 3

Not exactly, but you do have one option

Automatically increasing the gold acquired from an enemy wouldn't make sense in D&D (or, indeed any game).

However, you could gain access to the fabricate spell via the bard's Magical Secrets feature. You'd need to wait until level 10 to obtain the spell that way. Using the fabricate spell, you could turn raw materials into something more valuable.