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. Exit (wooden): De-select the cube and exit the editor.
2. Generate Structure Block (netherite): Create a structure block configured to contain the selected cube.
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. Holding the clipboard item, you can right-click to paste, or left-click to discard. (Do not destroy the clipboard item through any other means, or you may experience bugs!)

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 or pasted. 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 copied or pasted.
• 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.)