It is sometimes desirable to build something huge together with other players. For that purpose, sharing chest space helps. My locks mod was created for that purpose. And it works. However, it is tiresome to manually grant access to each user, and to have to always carry a keychain is a further disadvantage.
The Landrush mod contains a shared chest that is far easier to use: Instead of having to enter names manually, it just checks who's allowed to build in that area and grants permission to use the chest based on that information. The Landrush chest is limited to the Landrush protection system.
This chest here works similar to the Landrush chest, except that it's designed to work along all modern protection systems (those which use minetest.is_protected). So, now, who can take something out of the chest or put something in? Answer: Everyone who could dig or build at that position - provided the area is protected at all. Else it acts like a normal locked chest.
First, craft the chest:

After placing and opening the chest, you'll see the following:

Clicking on "Craft" lets you acces your craft grid directly. Just imagine coming back from an extensive mining tour, where your craft grid had to help out as storage space for additional ores, cobble or anything else. Now you don't have to transfer that stuff back to your inventory first. You can also take materials out of the chest, craft them in the grid, and place the result back into the chest without having to go through your main inventory.

Clicking on one of the bags buttons works only if you have unified_inventory installed. In that case, you can access your bags directly - same as with the craft grid above.

"DA" stands for "drop all". It will try to move all items from your selected inventory (either the main one, craft grid or a bag) to the chest. Doing so with the above setup leads to this:

"TA" is "take all" and tries to take everything from the chest and stuff it into your inventory:

"SA" means "swap all". It swaps both inventories as far as that's possible. Positions are kept. First, let's apply that command to the main inventory from above:

Now we switch to the bag shown before:

..and swap inventories. As the bag is smaller than the chest's inventory, only as much as is possible get swapped:

The last button, "FA", means "filter all". This may be less intuitive than the options above. The purpose of this button is to speed up dropping of gathered items into chests that are already sorted. You may have organized your chests in such a way that one contains only cobble, while another one might contain ores and ingots, another one wood etc. If you click on "FA", only items where there's at least one of them already in the chest will be transfered into the chest. It's like "drop all", except that what's already in the chest acts like a filter. In our above case, the shared chests, tree, wooden roof and glass are present in both inventories and thus get all transfered into the chest:

This blue shared chest can also be used as a tool to upgrade other chests. Wield the chest and punch another normal, locked or shared chest:

Clicking on the "shared" version costs you 2 steel ingots and upgrades the normal chest to the shared version introduced here. The chest's inventory is kept!

You can also downgrade chests. If you, for some reason, want to go back from the shared chest to a normal locked one, you'll get one steel ingot back:

Download: https://github.com/Sokomine/chesttools/archive/master.zip
Browse code: https://github.com/Sokomine/chesttools
Version: 0.1
Licence: GPLv3
License for textures: only contains re-colored textures from the default locked chest
Depends on: default
Supports: unified_inventory