| name | roblox-building |
| description | 3D builds via MCP, CSG operations, spatial coordination, Part properties, map design. |
| last_reviewed | "2026-05-27T00:00:00.000Z" |
When to Load
Load when building physical geometry in Roblox Studio via MCP (execute_luau / run_code) — single objects, room-scale structures, or multi-zone maps. Covers CSG operations, spatial coordination, and platform quirks. See references/full.md for complete patterns, build process, and validation scripts.
Quick Reference
MCP Statelessness (CRITICAL)
Every MCP call is a blank slate. Re-acquire refs at start of EVERY call. Never guess coords from chat — READ from workspace first.
local model = workspace:FindFirstChild("MyBuild")
if not model then model = Instance.new("Model"); model.Name = "MyBuild"; model.Parent = workspace end
Player Scale
Player ~5 | Door: 4w×7h | Ceiling: 10-14 (rooms) | Counter: 3.5-4 | Seat: 1.5 | Path: 6+ wide
Spatial Patterns
- Geometric Manifest: Named dims table (
Def = {Width=6, Depth=3, ...}), no magic numbers
- Relative Positioning: All sub-parts offset from anchor CFrame, never hardcoded world coords
- Grid Snapping: Snap to 0.125/0.25/0.5 stud increments
CSG Essentials
- Epsilon Rule: Cutters overlap boundaries by ~0.05 studs (coplanar = Z-fighting)
- Safe Wrapper:
pcall SubtractAsync/UnionAsync, verify result:IsA("BasePart"), copy CFrame/Color/Material
- Rules: Shallow trees. Build near origin, PivotTo destination. No MeshPart/Terrain.
CollisionFidelity.Box on decorative unions
Platform Quirks
- Cylinders: Extend X-axis. Rotate 90° Z for upright | Wedges: Tip +Z default,
-π/2 X = up
- Neon: Glows no light — add PointLight child | Defaults: Always
Anchored=true, explicit Color/Material
Anti-Patterns
Guessing coords | Unanchored | Hardcoded positions | Block-only | Silent CSG fails | >30 parts/call | Default gray
Build Process (Objects)
Assess → Plan (named dims, anchor) → Build (relative offsets, ≤20 parts/call) → Validate
Build Process (Maps)
Layout → Ground (floors, Origin) → Zone shells → Landmarks → Fill props → Environment (lighting, spawns)
Map Folder Structure
workspace/MapName/ → Origin (0,0,0), Terrain/, Zone_*/ (Floor, Walls/, Props/), Landmarks/, Lighting/, Spawns/
