Melon Toolkit is a planning utility for sketching builds, estimating physical properties from real materials, and preparing hitbox outlines as JSON — built for quick iteration on iPhone and iPad. Work stays on your device: contour detection uses Apple’s Vision framework, and material data is bundled locally in the app. Blueprint lab Lay out rectangles, circles, and bars on an infinite grid. Connect parts with pivot or weld-style joints and watch live mass and balance readouts update as you iterate. Mass & materials Choose from a built-in material library, adjust volume and quantity, and review totals for weight, friction, and a simple durability hint — useful when you are comparing options or sanity-checking a bill of materials. Hitbox helper Pick an image or start from a demo silhouette. Vision traces the contour on-device; refine the polygon by dragging points, adding or removing vertices, then export clean, readable JSON for your workflow. Important Melon Toolkit is an independent helper for players. It is not affiliated with, endorsed by, or sponsored by Melon Playground or its publishers. All trademarks belong to their respective owners.