Hell if I lived out there I'd find a way to smelt metal and just get a die for bottlecaps and just start making em.. I dont know why there wasnt a person who did this in the Fallout universe.
Well sure you could do that. Essentially a bottle cap is a unit of metal. Metal objects tend to be recyclable and fashioned into other objects by those who know how to go about doing it (such as the engineers from the brotherhood of steel, and adytum/boneyard, etc)
10 bottle caps are worth a "scrap metal"... so i don't see why its so confusing. A bottle cap is a widespread, unit of metal. you could use paper clips, thumbtacks, beer cans, ring pulls, anything like that, but a bottle cap is an excellent device since there are lots of old soda machines lying around. and you could use other things like tin cans as a unit of currency if you wanted to, or BB's, or bullets, or energy cells, etc. and you essentially DO use these things as currency in a barter based economy.
Also yes, it is very reasonable to assume that on the west coast a more "symbolic" form of currency was adopted, such as paper money reinstated by the NCR to replace the new reno drug trade, and regulate the gold and uranium trading of Redding and Broken Hills
I think some kind of new currency should appear on the East Coast, preferrably something in regards to "energy" maybe... bottle caps works well, but if you had factions accepting different kinds of currency that could work nicely. I dont think you can trade with the Enclave (haven't gotten that far) but you could like trade the prewar paper currency you find with them, since they are essentially neocons trying to revive dead government and economy with it, haha!
Most residents of the wasteland would definitely favor bottlecaps, since they'd have the necessity to recycle... And the brotherhood of steel would provide the engineering capability to make it happen, in addition to the scientific understanding and ability of actually making new materials, constructing new things out of base metals, etc... Maybe another faction, such as androids or robots or something could use portable energy sources, like microfusion cells, or something like "filaments, conductors" things like that... components used to fabricate electrical relays, computer parts, etc. as a form of currency. They could simply offer you more money for those sorts of items... something like this would add a new level of depth to the game, and what sorts of items you barter to certain types of people.
And of course, A food/water economy would make the most sense of all. Theres a lot of food in the game, and like that guy who is thirsty for water... i'm sure lots of wastelanders and traders would pay premium amounts of caps for food.
So for this game, you could actually make something that is a "ratio table" of values for different items that every "tradable" character responds to accordingly
Something like this:
.5
.25
.75
1
these values would represent
(Aid)Drugs, food (.5)
Weapons/ammo, bottlecaps (.25)
Electrical components, energy sources (.75)
paper money (possibly other special prewar items, like a picture of elvis for instance) (1)
This would be something along the lines of what I'd imagine a enclave faction correspondent to value. They have lots of prewar weapons technology stockpiled, since they are the government. So they wouldnt care about weapons as much, and they are isolated from the rest of the wasteland, so they definetely wouldnt use bottle caps. They could use energy sources though, and probably would have some interest in that (I mean, they made their West Coast HQ on a [censored] oil rig), and well the paper money would make sense for the Enclave, as it would be something they believe in, the united states of america, lol
Your typical wastelander, like a resident of megaton, would look something like this
.75 (Aid/food)
1 (weapons, ammo, bottle caps, scrap)
5 (energy sources, electric components)
.25 (paper money, pre-war artifacts)
Essentially prewar stuff, like paper money or... "who is that guy on the fuzzy painting???" would mean little to nothing to these kinds of folks. They are too busy worrying about the next raider attack, who want what weapons and drugs they got. agriculture is difficult in the wasteland, as its tough for things to grow. and while energy sources are useful, its unfortuante that most of these kinds of people have little hope of getting such items to actually function, or implement them in their low tech "civilization"... they are able to recycle basic metals, and doing things like craft suits of metal armor. And they can even melt down bullets with the right casings and molds, melt bottle caps into brass shell casings, etc. with the aid of larger communities, like the brotherhood of steel though.
This kind of economy would make a lot more sense that i've outlined, as it would be by faction... it would work especially well for an MMO