Selection & structures

Select a region, transform it, and save it for reuse.

• Select — drag a box selection. The dock's Selection section opens with the tool and shows live W × H × D and a block count (with a block histogram) at its bottom, plus Frame to recentre on it.
• Magic wand — click a block to select every connected cell of the same kind, or all of that material within a radius. Copy / Cut / Fill / Clear follow the exact selected shape, not just its bounding box.
• Include mobs — a tick under Box select. With it on, the mobs standing in the box count as part of the selection: Move, Copy, Paste, Clone, Stack and Clear all take them along, so moving a barn moves the animals in it. A mob belongs to the box if it is standing in it. Off by default, remembered between sessions, and one undo reverses the blocks and the mobs together. A copy made with it on keeps its mobs — pasting places them again, and rotating or flipping the clipboard first turns them with it.
• Move & Clone — reposition or duplicate a selection by dragging 3-axis handles; a green ghost previews the destination. Apply (or Enter) commits it as a single undo step.
• Apply modes — the Selection section's Apply list shows all 8 fill and convert modes as a radio list; picking a row expands its parameters right there, and Apply to selection (below the list) runs it as one undo step:
  • Solid fill places the active block everywhere; Hollow shell, Walls only, and Sphere / ellipsoid fill just part of the box.
  • Replace a block swaps one exact block for another — set From and To in the expanded row. Swap material changes the material but keeps each block's form (oak stairs → spruce stairs); Recolour changes the dye and keeps the block.
  • Blend two blocks mixes the active block (A) with a second block (B, set from the active block or left empty): Noise for an organic speckle, or Gradient (X/Y/Z) for a smooth ramp, with a Mix slider for the balance.
• Clipboard transforms — rotate a copy 90° about any axis, flip it, or scale it before pasting.
• Save as structure — save a box or magic-wand selection to the Structure Library to re-place anywhere or export as .mcstructure (magic-wand shapes keep their exact cells).
• Make structure (7) — a dedicated toolbar tool for exactly that flow: drag a box around a build (adjust it with the face handles), type a name in its panel, and Save to library — the Library opens with the new entry ready to Place or Stamp.
• Stamp — pick Stamp on a Library structure, then click or click-drag to lay repeated copies (spaced by the structure's footprint); a footprint preview follows the cursor, and the whole stroke is one undo.
• Analyze blocks — a tally of what's inside the selection: a sorted histogram of block types with counts and percentages, live at the bottom of the Selection section whenever a selection exists.
• Gravity — settle the blocks in a selection downward, per column (relative order preserved), as if affected by gravity.
• Fill water / Drain — flood a selection's empty cells with water, or remove water from a selection.

Structure Library

The Structure Library (the Library button beside Make structure, or 8) holds your saved structures — it persists across reloads and ships with a few built-in starter structures (a tree, cottage, well, and watchtower) you can place or stamp right away. Each saved structure shows a small rendered preview thumbnail so you can tell them apart at a glance. Place drops a structure in as a live preview you can move with the 3-axis handles (the Library stays open — position it, then Apply or Discard); Stamp repeats it along a click-drag; Save downloads it as a .mcstructure file.

To generate structures with AI, connect an agent over MCP — see AI agent (MCP). The agent builds with the same undoable ops and can save its work straight into the library.