I think I'd probably pack a bed, TV, microwave, and mini fridge into it and go travel and see a bunch of the world without worrying about lodging. I could also use it at work to eliminate my commute and save myself the high rent of living in Northern Virginia lol.

Magical room with free power and Internet... I'm making it into a server room!

I'll tell you what'd I'd do, man. Two chicks at the same time

Paint the inside beige and rent it out for $2000/month

Man, the places I could hike without having to carry a pack! Wouldn't need to plan for resupply or anything. Would have communication access from anywhere in the world.

You could use it as a kickass home gym where you can dial up or down gravity depending on what you're doing.

Smuggling would be a whole lot easier if you went that route. Transporting all sorts of things really; you only need to get yourself to the new location.

Could do some very amazing magic tricks since you can disappear (and swap props or outfits or whatever).

With gravity turned down you could presumably build up some momentum and launch yourself places. Not sure how you'd stick the landing unless you can control which way is "up" as you teleport to the room.

Edit: Just realised this idea is kinda similar to an ability from HunterxHunter

break top

break bottom

insert shit ton of rocks

set gravity to 2g for faster gravitational acceleration

I have acquired rocks that can keep falling and build up velocity forever.

live life as usual; when I'm old enough to near death, aim for anywhere within the planet with said rocks.

Assuming I fill the 3x3x3 box half to half with sandstone and air; its weight will be 33kg.

If I live for 70 years more, assuming the gravitational acceleration is 19.72 m/s^2; I can generate stones that can go up to 156.8 billion km/s (or 145 times the speed of light)

Using the kinetic energy formula; I'm pretty sure unleashing this anywhere will be enough to destroy a huge chunk of the existing universe and in the end I'll be the person to go out of the world with the biggest bang.

Well, specifics about the big bang is not known; but I'll be its closest contender if it is correct.

Cameras in every corner and hold the world monopoly on 0 g porn.

How about just living in it.

Assuming that I can take it wherever, and when I’m in it, no one can see any trace of it…

I would find locations where valuable items would be in the near future. Go to that place, hop in my box, and wait for night fall. Then I would magically materialize in a strange masked bandit costume, rob them blind, and disappear. Then pop out a few days later in different clothes to make my casual exit.

Ideally, I’d go in and out inside a bathroom nearby so it’s less conspicuous.

I'd probably use it as having a lot of extra portable storage space, so it'd probably get filled up with a bunch of junk real fast. also I'd have the coolest battery pack

This is a terrifying power, I gotta say. Like a dude could carry an entire armory around and deploy it Looney-toons-style wherever he wanted.

I would probably just put a bunch of shelves in it and use it as a personal EDC gear storage space. 3m^3 is more than enough space to store pretty much anything you might need in a jiffy.

There's also apart of me that thinks putting a bed in there would mean not having to bring a date back to your place or to a hotel - but being real I'd probably never use it if I set it up like that.

Some ideas:

1. A fast way to dig holes, if 'soil' or 'stone' is an object.
2. Annoy physics teachers -- move in and out to drive a piston. Perpetual motion!
3. Moving day is easy.
4. Server farm.
5. Safe house.
6. Is momentum conserved? Not sure how general relativity would work. Win a Nobel Prize.
7. Building stuff in space just got a lot easier and safer. 27 cubic meters of free payload!

I would get a metal rod of four meters, and teleport into the pocket universe to see what happened.

As others have mentioned - I'd use it as a hotel room and travel the world. I wonder if becoming a courier could fund the travel costs.

*You can only teleport out to where you teleported in from.

Does this mean you get dropped into outer space if you stay inside for more than checks notes ~4 minutes?

Long trips on planes/trains/busses would be a lot more enjoyable.

Emergency supplies would be available at a moments notice including escape from the elements (camping/travel just became a breeze) .

Would you be able to free dive super deep taking each breath or a rest in the pocket dimmension?

2g weight room. I would train some rabbits to pull weights. Then take my rabbit beasts out after 6 months and have them pull me around town in a sled.

If I bring luggage or a person in with me, can I leave them there for a few hours? Would they have a way to get out if something happens to me? (Travel just got easier in my mind)

Edit: also, did you mean 3m x 3m x 3m, or 3m^3, which is 1m x 1m x 3m?

*There is an eject button for those inside to get out if something happens to you

Well there goes one idea...

*Time proceeds at the same rate inside the pocket dimension

There go a couple more...

I'd go camping. Travel around the world. Become a cleptomaniac. The usual stuff...

Three cubic meters, or a cube with three metre sides?

It sounds really boring but... Reading nook - just a little spot to relax and read. Kit out the floor with pillows, the walls with shelves, and paint the ceiling to look like the sky.

So... Like a Pokeball for humans? 🤔

Can I only teleport back to where I teleported in from, or can I teleport out of the cube to anywhere I want?

Well, feel like I could quite easily become a very famous stage magician a la "The Prestige" which would help make me rich while letting me keep the pocket dimension thing hidden in plain sight so to speak.

But my mind, as always, races to the limits more so than the possibilities. What would happen if I bring in more stuff than would fit? Say I bring in a decimeter cubed of concrete over and over until I no longer fit inside the cube if I'm allowed the concrete with me in? What if teleport in while driving? Does the car come with even though it doesn't fit? And if I return to the spot I entered does that mean I'll plopp out on the highway while my car is wrecked a ways down the road or inside my mangled car? What if the space i entered from is occupied or otherwise lethal?

What if I teleport in while under water? The void i leave in such an instantaneous fashion would behave quite interestingly if I did it at great depth.

edit: oh, pocket dimension... i just thought it said "pocket"...

whatever, i'm leaving it :P

No mention of external dimensions, so I am going to assume that it exists in the abstract since you mention teleportation. Like you just think about it and teleport there, not carry it upon your person like a portable hole in D&D.

Like others mentioned, a living space of some kind. I'd worry at first where I teleport inside, like hopefully not inside my mattress. Also, when I teleport back out, where is that? Where I teleported in? What if that gets replaced, like say I popped out while in an empty parking garage, but popped back in and a car is now parked where I left off? Might be nice if I pop back out anywhere I choose. Pop in while in New York, pop out in London.

Man, I'd save so much on rent. Or at least storage.

I would ask writers Game masters and gamers to use the item in their stories/games and see what uses they come up with i would never thought of on my own

Whike waiting for that to come to fruition ide look for a passable look a like to team up with.

Then i would figure out how the teleporting works. If it maintains speed/velocity/vector/momentum

test if i could jump from really high, pop into my pocket dimension just before hitting the ground cancelling out the speed i was falling when i pop out of the pocket dimension

it'd be a great place to grow some weed.