This is a simple command block that clones the trapped chest below it, when triggered by the trapped chest on top.
Both chests must be "trapped chests" so that they can trigger the command block.

Note: Minor issue, sometimes when right-clicking to open the top chest it does not open and requires right-clicking again.
This is just because it is resetting the chest contents first.

You can swap any of the items in the bottom chest and they will appear in the top chest.

Confirmed commands work in Minecraft 1.12.2, 1.16.4, 1.17 and 1.18.

Just copy and paste one of the below commands to use. There are 3 separate examples in case you are tight on space.

Commands:
Example 1
/clone ~0 ~-2 ~0 ~0 ~-2 ~0 ~0 ~2 ~0
Example 2
/clone ~0 ~-1 ~0 ~0 ~-1 ~0 ~0 ~2 ~0
Example 3
/clone ~0 ~0 ~1 ~0 ~0 ~1 ~0 ~2 ~0

Why this version?
The map was made in Minecraft version 1.12.2, so they can be used and edited in MC Edit, and used for modded sky worlds, or other modded packs (as mods are always a few versions back).

**Usage Rules**
If you use this map for streaming, please link back here then other people can download the map. Feel free to use all or part of any of the buildings in your own worlds or modpacks, just leave a link back here in appreciation and do not re-host the original file.

Enjoy,

Rogue

PS - If having problem's downloading with Drop Box, try one of the following:
1 - on the right side of the screen there are 3 dots that say "More" if you hover over it. Just click and select "Download".
2 - on top the right (next to sign up" there is a down arrow, just click and select "Download".

This is because of something Drop Box has changed at some point (rather then allow direct downloads).