Reasons to make containers: Faster handling of items. Storing of items. Transporting/logistics. Will make everything faster and should be easy to understand/handle, cause basically nothing changes. Will enable to scale the game to an incredible throughput, which is eventually needed to achieve the game-target. Makes trains more useful.
Basic idea about containers
Containers are slots! A chest has slots and one slot is like a container. (Means, that a container can contain a number of items of one type)
A container has like a slot no intelligence. You cannot control which item is filled into a container/slot. The first item filled in determines all items (it's like a slot). This can only be controlled by filling it.
Graphical representation
Imagine a container like a barel-like form made of a steel plate. On the outside of it the containing item is printed and about how full it is (100%, 50%, 10% or empty). Its eventually bigger than normal items (see next).
Size on belts
A container is maybe "bigger" than a normal item and takes both sides of a belt!? (just an idea...) I think this is also needed to distinct a container from an item and to see about how much is inside it, otherwise it would be too small.
Handling
A container can be handled like a normal item, when taking it up. It takes one slot and shows which item/how many are inside.
When you need to open a container (e. g. you craft something or take one item out of it) the container-hull is destroyed and the items in the container remains as slot-items. The game-logic tries to avoid destroying containers as long as possible and tries to use single items first.
Inserters
A container can be handled by the inserters like a normal item. (I think the idea of having only special inserters doesn't bring the game forward). Filter inserters works also with containers as known.
Auto-repacking containers
When in a chest or in the inventory the last slot is used an automated refilling tries to fill non-empty containers with the same item into one to make slots free.
Filling stations (creating a container and filling it)
A filling station works a bit like an assembly-line: Its about the same size (or smaller, 2x2). It takes some items to build a container (one steel plate?) and has an input-door for the stuff, that is filled into the new container (with a cone?). The input doors can be imagined like in the factory-idea ( https://forums.factorio.com/forum/vie ... t=20#p7318 ), the input.door is, where you put a belt into it, the output-door, where you place a belt out of it. When the container is full, or after some time (like the train-station) or when filled for a minimum percent, the filled (or empty or not fully filled) container comes out of the output-door. I think it is important, that the filling doesn't take inserters, because this needs too much energy/time and this will destroy the advantage of containers.
Inside of the filling station
It is pure purpose, that it will make problems to fill a mixture of items on the belt into containers (because the filler has a internal buffer slot, the second non-matching item blocks the rest!).
Assume we have a belt full of iron-ore and we will fill it into containers. The iron ore is stored into the buffer until the container is built. When it is built, the buffered iron-ore falls into the container and the rest is filled from the belt. Now there is a single item of copper ore on the belt, because we built a mine to near to the copper-field. The copper will go into the buffer, also other copper-items, while the iron-ore runs through. When the iron-ore-container is full it is put on the output-belt and the next container is filled with copper-ore, because it is in the buffer. So this container is not very full, because we have said that it is packed after 30 seconds. But meanwhile, the iron-ore in the buffer was refilled. This works well unless a third item (cole) is on the belt. This blocks everything because there is no buffer left for it.
You can craft a container yourself (every empty container takes one slot) and put stuff into it until it is filled.
Put the things out of the container,
Because it is just pure thin iron-plate a container is not reuseable. Taking out an item destroys the container hull and the items remain in the slot. Of course the container must be inside a slot before. If not, it behaves like a box, which is picked up if you inventory is full.
In chests
A inserter which outputs things from a chest tries first to output lose items. If there are no left it opens the containers (destroys them) by using the lower filled containers first.
In assemblies
If an inserter puts a container into an assembly, the slot must be free before. This means, that a mixture of lose items and containers will only eventually work, because the slot must be completely free before inserting a container in it. (The assemblies need to have as many input-slots as items needed.)
This means also: Inserting from a chest to a assembly doesn't destroy the container, the container is just put into the assembly (again: only possible, when the slot is empty before).
An alternative way
would be to have unpack-stations, which works similar to the filling-stations. But I don't like this idea, because it is complicated enough; fill and unpacking has also it pitfalls, e. g. a container cannot be unpacked, if there is no empty slot, so I think this is complicated enough.
Logistic robots & containers
Logistic robots can carry a whole container. Maybe a research is needed for that.This enables to have much less logistic-robots than now and with them the container-idea makes much more sense, because todays logistics is nearly impossible without containers.
Priorities
The logistic robots try to transport containers first, even if the way is a longer (no idea how much? about double as long?). With this mechanic we try to force the player to use either containers or lose items, because inserters try to use loose items first.
Containers and assemblies
This is not ready thought to the end: When you have logistic-robots in this stage and your factory throughput is high enough to fill a container within seconds (>200 basic-items per minute!) you can research that logistic robots can put a hole container on an assembly-station (no inserter needed anymore to put the container into the assembly). This means, that you don't need input-inserters, input belts etc. anymore. But you will need output inserters/belts of course. This should speed the game extremely up but keeps it interesting and makes it possible to introduce a LOTS of new items.
Container yard
A container yard can imagined like a "hall of (provider)-chests". It is therefore of course much bigger then a chest (4x4 to 7x7?).
Because you cannot insert single items, a input-container-crane takes containers in it when you move a container to the "input-area".
I think there should be no filter. Every container is put by the crane into it.
Like a provider chest
Because the container storage works similar to a provider chest, logistic robots can put and take containers from here! (The crane is only to connect filling stations directly and to get over the time, when you haven't researched logistic robots).
Provider chest vs. container storage place
This is perhaps another topic: the provider chest are currently not very useful, because you don't have any control about what should be stored inside. I think it should be removed! Instead only the container yard can be used and it should work similar to the storage-house in Siedler3, where you can just say, which items (and here also how many slots of them) should be stored inside. This makes a provider chest not a requester chest! Only currently unused containers are stored here and this behaviour depends also only the logistic robots, not the input-crane!
Logistic networks
works similar to everything else. Cable it.
Wagons
Just like in a chest. A single inserter can fill a wagon within seconds with containers. Makes much sense and gives Locomotives much, much more sense, because you don't need a buffer-chest in front of the wagon anymore.
Railway station and other transports
I can imagine also that a "railway station" is nothing else than a combined filling station/container yard. When thinking further, this is also the only way to transport items over water with a ship (harbor) or airplane.
Destruction
When destroyed a container behaves like a chest.
Research/Balance/How early in the game?
I would say, containers/filling-stations should be available before logistic robots. The container yard should be available at the same time with the logistic robots, but must be researched extra.
