What would a reasonable "magic inventory bag" sound like?

Zombocalypse

So if I'm roleplaying in ESO with other players and I want to pull out an item, is there some lore-friendly way to go about it other than coincidentally having it as one of three items from your character's imaginary backpack?

Maybe some conjuration spell that enchants a satchel/bag that can conjure your item from a tiny pocket of Oblivion that has your possessions?

notyuu

Lore wise these nothing saying that what you summon via conjuration has to come from another plain the reality, for example in oblivion you can literally get a spell to summon a bear, not a magic bear, not a daedric bear, not a divine bear, just a normal, nirn based bear, so in theory you could use conjuration to bring you any item, but then the question becomes, if you conjure food stuffs and eat it, does it fade from your stomach when the spell wears off? As that happens with every other thing brought fourth by conjuration...

Benzux

Conjuration magic is specifically referred to as the summoning of creatures or items from another plane of existence, so it would be possible to imagine storing items in some small demiplane of Oblivion (which we know there are innumerable amounts of) to then conjure forth as needed. How proficient a mage has to be in Conjuration magic to be capable of this, however, is another question entirely, but I do not think just about any novice would be able to do it.

On a tangentially related note, the Overlord light novel series provides an interesting solution to the conundrum posed by notyuu, though from a slightly different perspective. In that series, healing magic that is used to, say, regrow a lost limb causes the original limb to disappear. However, if the original limb has been transformed/processed enough so that it no longer constitutes as a "limb", such as by being eaten by a monster and digested, it (or, in this case, the nutrients, energy and waste it turned into) doesn't disappear. We don't know if any of the Earth Bones govern this specific aspect of magic and natural laws, but if similar logic is found, then that might be a sufficient answer.

AcadianPaladin

For roleplay, my character manages inventory in two ways. For things she needs somewhat routinely, she stores in the mage pouch (bag of holding) she wears around her waist (pretend). This sort of replicates her backpack. Though the mage pouch holds basically unlimited volume and weight, things can get a bit disorganized in there with too much stuff. So she also has a summonable magic storage chest, for which we use the 'crown store' emote. We view that as similar to her bank - she can access it in the field, just takes a bit more time/effort.

Nestor

The player character pulls a bag out of their pocket. It stretches out as they reach into it, all the way up to their armpit. You see the bag move around as the arm and hand are digging through the bag to find the desired object. Sometimes the PC looks in the bag with a puzzled frown, but eventually pulls out their prize with a smile on their face. The bag then shrinks back down to a small size to be placed back in the pocket.