World Edit Mini

You can run the command /function editor:get_items to get an "Open Editor" tool which, when used, will select the block you are looking at, and enter Selection Mode. (You will also get a "Teleport" tool; this is unrelated and just for utility.)

In Selection Mode (where any number of block positions can be selected), these tools are available:

1. Toggle (gold): Select the block position you are looking at, or de-select it if it is already selected.
2. Exit (wooden): De-select all selected blocks and exit the editor.
3. Convert to Cube (diamond): Find the smallest cuboid containing all selected positions. Select this cuboid (deselecting all positions), and switch to Cube Mode.
4. Set Blocks (stone): Set each selected block to the block you are currently looking at.
5. Move (iron): Move all selected positions by one block in the direction you are looking.

In Cube Mode (where a cube(oid) is selected), these tools are available:

1. More Options (book): Open the secondary Cube Mode menu.
2. Exit (wooden): De-select the cube and exit the editor.
3. Fill (stone): Fill the cube with the block you are looking at.
4. Convert to Positions (diamond): Select one position at each corner of the selected cube. De-select the cube and switch to Selection Mode.
5. Move (iron): Move the cube by its size in the direction you are looking. (For example, if the cube is 2 blocks high and you are looking up, it will move 2 blocks up. If you want to move by 1 block, convert to positions first.)
6. Copy (copper): Copy the selected region to the clipboard. You will get a new "clipboard item" representing the copied structure. While holding the clipboard item, you can right-click to paste, or left-click to discard the copied structure. (Do not destroy the clipboard item through any other means, or you may experience bugs!)

In the secondary Cube Mode menu, these tools are available:

1. Back (book): Return to the main Cube Mode menu.
2. Select Same Blocks (gold): Select each block inside the selected cube which is exactly the same as the block you are looking at, and switch to Selection Mode.
3. Expand (diamond): Expand the selected cube so it contains the block you are looking at.
4. Generate Structure Block (netherite): Create a structure block configured to contain the selected cube.

Have fun! :)

A few notes:

• As the "fill cube" method is relatively inefficent due to command limitations, /gamerule max_command_sequence_length (by default set to 65536) determines (approximately) the maximum number of blocks that may be filled. You may wish to set this to a larger value (for example, /gamerule max_command_sequence_length 16777216).
• Similarily, /gamerule max_block_modifications (by default set to 32768) determines the number of blocks that may be copied, pasted, or filled at once. You can set this to a larger value (for example, /gamerule max_block_modifications 2147483647), however the server may slow down or crash if lots of blocks are being modified.
• If you find any bugs, let me know! (I'm on Discord!)

(Disclaimer: I haven't used WorldEdit and have no idea how it works, but I wasn't really sure what else to name this datapack. I just made this because I wanted to be able to use /fill easier, and use copy-paste.)