List of abilities that let you squeeze through a 1-inch gap

Question

According to rumors, the Fairy race will no longer have the ability to squeeze through gaps that are 1-inch across, so basically I’m looking for other ways to achieve the same effect through items, class abilities, etc.

For more clarity, what I mean by “achieving the same effect” as the UA fairy race’s ability is the ability to squeeze (not teleport) yourself (without the help of another) through a 1-inch gap using a resourceless ability. Things like an arch druid’s wildshape (as mentioned by Thomas Markov) for instance. The purpose would be to move through a demiplane filled with portable holes on easels with a 1-inch gap between them (so as to greatly increase increase the effective volume of the demiplane).

Answer 1

The Moon druid’s Elemental Wild Shape feature (and possibly some vanilla Wild Shape options)

The Circle of the Moon druid’s Elemental Wild Shape feature description states:

At 10th level, you can expend two uses of Wild Shape at the same time to transform into an air elemental, an earth elemental, a fire elemental, or a water elemental.

Of these, the air, fire, and water elementals have traits that allow for moving through spaces as small as an inch.

This method possibly extends to any druid, subject to DM ruling. There are stat blocks for some very small creatures, such as a spider, and your DM may allow you to Wild Shape into a sufficiently small spider.

At 20th level the Archdruid feature allows Wild Shape to be used an unlimited number of times.

True polymorph/shapechange

Using either the true polymorph or shapechange spell, one can transform into any of the numerous monsters with the Amorphous trait:

Amorphous. The [creature] can move through a space as narrow as 1 inch wide without squeezing.

This method also works for the elementals mentioned in the last section.

Gaseous form

The gaseous form spell works as well:

While in this form, the target's only method of movement is a flying speed of 10 feet. The target can enter and occupy the space of another creature. The target has resistance to nonmagical damage, and it has advantage on Strength, Dexterity, and Constitution saving throws. The target can pass through small holes, narrow openings, and even mere cracks, though it treats liquids as though they were solid surfaces.

This spell also has a potion version that applies the effects of the spell.

Kyrzin's Ooze

As Deeds observed in this answer, Eberron: Rising from the Last War features a very rare magic item called Kyrzin's Ooze that can grant the ooze's Amorphous feature to the character for 1 minute, once per day. While this technically fulfills the role asked about in the question, it's going to be a tough fit as a sort of "generic" option. It's an item tied very closely into the lore of Eberron, and the magic item description even references the Daelkyr, the emissaries from Eberron's Realm of Madness, Xoriat. Apart from true resurrection, dying while attuned to this ooze likely means you cannot be resurrected:

If you die while the ooze is inside you, it bursts out and engulfs you, turning your corpse into a black pudding allied with the daelkyr

Answer 2

The Kyrzin's Ooze magic item from Eberron: Rising from the Last War allows this as well (though it has some properties similar to a cursed item as well). Here is the relevant text from the item's description (page 278):

Amorphous. As an action, you can speak a command word and cause your body to assume the amorphous qualities of an ooze. For the next minute, you (along with any equipment you're wearing or carrying) can move through a space as narrow as 1 inch wide without squeezing. Once you use this property, it can't be used again until the next dawn.

Answer 3

In addition to the other answers, the 14th-level feature of the Aberrant Mind Sorcerer, called Revelation in Flesh, also works:

Beginning at 14th level, you can unleash the aberrant truth hidden within yourself. As a bonus action, you can spend 1 or more sorcery points to magically transform your body for 10 minutes. For each sorcery point you spend, you can gain one of the following benefits of your choice, the effects of which last until the transformation ends:

• [...]
• Your body, along with any equipment you are wearing or carrying, becomes slimy and pliable. You can move through any space as narrow as 1 inch without squeezing, and you can spend 5 feet of movement to escape from nonmagical restraints or being grappled.