Are there any specific non-magical ways to create areas of heavily obscured vision?

Question

Inspired by this comment which states that beholders can't use eye rays in heavily obscured areas I started thinking that things like fog cloud would be cleared by their anti-magic eye which would limit the benefit.

So, is there any way that a similar effect to fog cloud can be created that will not be suppressed in an anti-magic field?

I am not looking for creative DM fiat answers (Like creating water on top of a bonfire cantrip) just things that are specifically covered within the rules (Such as a non-magical potion of fog if such a thing were to exist).

Note: Other things that obscure vision such as darkness are not what this question is about. Fog cloud is physically obscuring vision so darkvision etc would not be of benefit. The solutions need to come up with similar physical impediments.

Answer 1

Smoke grenades

In Chapter 9 of the DMG, explosives are introduced as option for the DM to allow in their game. One such explosive is the smoke grenade which is completely mundane and creates a heavily obscured area:

One round after a smoke grenade lands, it emits a cloud of smoke that creates a heavily obscured area in a 20-foot radius.

This seems to be the only concrete case of a defined, non-magical technique to create a heavily obscured area currently in the rules.

Note that this is an optional thing that cannot be assumed to exist in every game. Ask your DM if they'll allow it (or some modification of the idea).

Unearthed Arcana: Smoke Stick

There is one option outside the currently released rules in the Alchemist subclass of the Artificer Unearthed Arcana class.

Smoke Stick. As an action, you can reach into your Alchemist’s Satchel and pull out a stick that produces a thick plume of smoke. You can hold on to the stick or throw it to a point up to 30 feet away as part of the action used to produce it. The area in a 10-foot radius around the stick is filled with thick smoke that blocks vision, including darkvision. The stick and smoke persist for 1
minute and then disappear. After using this formula, you can’t do so again for 1 minute.

This is not a piece of equipment though, but a class feature. However, it does provide another rule option (albeit in playtest form) that indicates how creating non-magical smoke would/could work.

Answer 2

Smoke would cause a visual impairment that results in concealment. The thickness of the smoke and thus the amount of concealment provided is up to DM discretion.

Although I can't find specific mention in the rule books, there is a precedent set by Hoard of the Dragon Queen:

Everything in the smoke is lightly obscured, and objects that are seen through more than 15 feet of smoke are heavily obscured.

Smoke is produced by trying to burn things that smolder instead of flaming; such as wet grass/hay, green leaves/branches, tar/pitch, etc. Of course, this requires that you have a well established fire or bed of hot coals to supply heat to these materials. The amount of smoke you can produce for a given amount of material is up to GM discretion.

The DMG lists a smoke grenade as a modern explosive weighing 2 lbs.

One round after a smoke grenade lands, it emits a cloud of smoke that creates a heavily obscured area in a 20-foot radius. A moderate wind (at least 10 miles per hour) disperses the smoke in 4 rounds; a strong wind (20 or more miles per hour) disperses it in 1 round.

An alchemical smoke bomb is possible. Mixing Potassium Nitrate(saltpetre) and sugar produces solid that smokes when burnt. Potassium nitrate was isolated from guano by soaking it in water, filtering it, and harvesting the pure crystals that grow. It may be produced in a similar manner from urine or manure. The availability of the chemicals and knowledge is up to DM discretion. Also, the GM may rule "side effects" for chemical smoke such as choking/coughing.

Answer 3

Prior editions have precedent

I have not found any official non-magical item that does what you want in 5e sourcebooks. Most likely, you're going to be dependent on your DM allowing whatever you do, which is technically the case even for things explicitly stated in the rules anyway. If you or your DM doesn't want to simply allow "Fog Cloud without spending any spell slots or other resources, and which cannot be dispelled because it's not magic" then you could negotiate an alchemical tool for the job. Alchemical tools do exist in DnD 5e, such as the Alchemist's Fire listed in the PHB, but none of them explicitly produce obscuring smoke. However, precedent from 3.5e gives the smokestick that could be ported to 5e. It's the closest I know of to "non-magical potion of fog".