You are going to live in a rustic cabin in the mountains for four months. What do you bring?

You will be sharing the cabin with several other like-minded people that you've never met before in a roommate dynamic.

"Hell is other people." I take something, anything, to provide myself a private space. Maybe even a tent so I can sleep separately away from everyone else. Even though a tent is uncomfortable, I'd prefer the physical discomfort of sleeping on the cold wet ground to the psychological discomfort of being forced to endure the company of strangers for a prolonged period. I have days where I don't cope with my one and only housemate - and he's pretty much an ideal housemate for me. Being forced to share with strangers who I'm probably not going to be compatible with is a good way to drive me mad.

Basic food storage (coolers),

Where does the food come from? Am I expected to hunt and forage?

Honestly, this scenario sounds like hell for me. Sharing accommodations with a group of strangers? No food? No electricity? No running water? I wouldn't cope at all. There's nothing I could bring which would make things better for me.

I'll second what others have mentioned above for the practical basics. You haven't mentioned the terrain or climate, but I'd add at least one satellite messager per group, and personal locator beacons given that you're building or clearing trails and it's easy for people to wander off.

Based on years of week-long trips with the Girl Scouts and solo expeditions, you're really going to want some options to minimize interpersonal tension, maximize team cohesion, and provide civilization-like novelty during downtime:

Eating is priority #1 when everyone's been walking and working all day - there are lots of opportunities during meals for entertainment and cameraderie that don't require much additional weight and space.

• Explore trail cuisine - bring seasonings, a variety of dried staples, sauces, and condiments to improve packaged trail food, or prep your own basics and give everyone a chance to adjust for their own tastes. Stock up as needed with postal delivery. Award small daily prizes (see item-crafting below) for most novel, tasty or awful concoction.

• Have everyone bring their favorite junk foods or beverages and share around, then go round-robin to advocate for why they're favorites. Compare and contrast, get friendly arguments going, etc.

• If you're in a spot where it's convenient and safe, take short breaks during the work day to forage for wild food in small groups, or pick near the trail as you move along. You'll want to bring a few spare baggies or stuff sacks for this. Chances are, there may be edible berries, wild asparagus and garlic, and other treasure-hunt finds during the time you're out for your trip. Bring it all back to the campsite, group-verify everything is non-toxic, and add to the night's meal.

Relaxation:

• Don't bring drugs harder than weed on the trail - that gets dangerous fast. Cannabis is generally a more manageable high than alcohol and helps with trail aches, but best shared around when you're safely settled in camp and bedding down soon.

• Light-weight sports equipment - frisbees, hacky sacks, and rubber balls in bright colors are harder to lose in woods and meadows. Waterproof playing cards are another great item.

• I'd add multiple colors of duct tape, Spectra cord, shoelaces, superglue, silicone, and water-soluble glues, Sugru, watercolor paints, Sharpies, small packets of wooden beads, sewing kits, etc. Not just for repairs, but so you can craft things together - wind chimes, dream-catchers, and macrame' lantern hangers for tents; small duct-tape bags (great for the toilet paper/trowel/hand sanitizer kit); temporary "tattoos"; decorated trail markers; and so on. If you want to get really artsy, there are usually dried grasses, vines, and bendy stems along the trail that can be woven into mats and baskets. Wood carving and whittling have already been mentioned.

• Small musical instruments - I'm personally not in favor of people playing and singing off-key, but there's a certain amount of mutual accommodation expected, and earplugs weigh nothing.

Cabin stuff:

• Hanging a lightweight ground cloth or thin cotton tapestry around your bunk can break up a space to enhance the feeling of privacy and personalisation.

• I'd bring a small solar or crank charger and e-Ink reader with a big library. Also, maybe a small portable MP3 player and earbuds. Depending on the group, a portable Bluetooth speaker.

• Trash paperback books - every cabin needs a library. Bring books, take books, trade books.

• Grooming supplies - scissors, razor, mirror, etc. The cabin visits are a perfect time for people to do monkey-type social bonding over hair.

I just thought of something you could take, if you were so inclined: boardgames. This is a way to keep all of you busy, without electricity.

You will be sharing the cabin with several other like-minded people that you've never met before in a roommate dynamic.

Deal breaker.

Cabin is for relaxation and getting away from daily life, not forced being together with people you don't know or trust.

I can bring anything, regardless of whether or not I actually own the thing in question right now?

I choose a truly obscene quantity of diamonds, so that once I leave I can threaten De Beers with flooding the market with them so they pay me a few dozen million. Or, for the chaos factor, the Pacific ocean.

In all seriousness though, people here are overlooking a vital piece of equipment. A deck of cards. You've got other people with you, and a deck of cards provides by far the most possibilities as far as number of games goes for any other object, let alone those of similar size. But not just any deck of cards; I choose a deck of uno cards. I know from experience that you can play it as-is for an hour a day for years without it getting the least bit old. And you can construct a normal deck from an uno deck by treating each color as a suit and substituting reverse, skip, draw 2, and 0 for the royals, but you can't do the same thing the other way around. Plus you can do other stuff with it (house of cards, etc.), and it's infinitely portable.

A meditation timer that isn't an app on my phone.

I'd want a lot of books, and to save weight & space I'd want them on my Kindle instead of dead trees. So that would also mean a hand-crank-to-USB thingy to recharge the batteries.

A good journal.

I enjoy the outdoors, so my focus would be more on survival and safety than explicit entertainment.

• Detailed topographic map of the area
• General field survival guide - Something like the US Army FM 21-76
• Location-specific illustrated plant and wildlife identification guide(s) - Essential to know what you're going to come across. What's poisonous or dangerous, what's safe or edible, what the presence or absence in an area might indicate, etc.
• Hatchet
• Hunting knife
• Sharpening stone
• Tweezers
• Compass
• Flare gun
• Flint & Steel
• Trench tool
• Basic fishing tackle (if there's a fishing spot nearby)
• Walkie talkie set
• First-aid kit
• Water purification tablets
• High quality hiking boots and socks
• Work gloves
• DEET
• Lightweight quick-setup tent (for the work days along the trail)
• Lightweight sleeping bag (for the work days along the trail)
• A good hiking backpack - Need a way to carry enough for the 9 days on the job
• Disposable camera - Low-tech, "no"-power way to document things. Since town is within driving distance, can develop in batches

• Condoms and lube. With 4 months, minimal outside entertainment and multiple like-minded people, even if we're "roommates" someone's probably going to need them unless there's literally no privacy ever.
• Alcohol. Lots of low ABV beer, for a light buzz after a long day. A little bit of hard stuff for special occasions or celebrations. It's also a pain to get shipped through the mail, so it's all the more important to stock up. That said, taking half a day to drive to town for supplies isn't the worst, so maybe no more than one month's supply, assuming it's possible to stock up during your 4 months.
• A whittling knife and honing kit. Whittling is a great thing to do when there's not a lot else going on, you can keep your hands busy while you talk, and you might make something cool. Just don't mix with the alcohol.

A lot of the practical necessities have already been mentioned, so all I have left to add would be earplugs, a mosquito net, a Swiss army knife, and a soccer ball... maybe a with a pump and patch kit just in case. I have no experience with camping or going off-grid but I think I'd be willing to manage with those.

A good trench tool and plenty of sunscreen. Maybe a few books I move been meaning to read.