Drop Points. Get a Solid.
Every other way of making a 3D model starts with someone else's shape. This one starts with nothing: a one-metre cube, an amber working plane you slide up and down, and a tap to drop each point. The skin rewraps live with every point you place or move — shrink-wrap the whole cloud with Hull, or stack exact circle slices into vases and hourglasses with Loft. It also answers a quietly unserved search: drop in a surveyor's or scanner's .xyz point cloud and get a watertight STL back, no desktop CAD, no upload.
Shrink-wrap or stack: two skins, two theorems
Ask a computer to build a surface through a set of points and you are really asking it to guess — infinitely many surfaces pass through the same points, which is why scanner software argues with itself about reconstruction. The convex hull is the one exception: the tightest skin that contains every point has exactly one answer, always closed, always printable. Imagine pulling cling film over a handful of nails hammered into a board at different heights — that is what recalculates here every time you move a dot.
The trade is that a hull has no hollows: it bridges straight across any dent, so an hourglass collapses into a drum — the waist points end up strictly inside the wrap, doing nothing. That is what Loft mode is for. Loft borrows the oldest trick in boatbuilding and CAD alike — the lofted hull, drawn as a stack of cross-sections — and treats every working-plane height as its own slice: each slice gets its 2D outline, consecutive outlines get stitched into walls, and the ends get capped. Wide, narrow, wide is now an hourglass, not a drum. Each slice is still convex on its own, but the stack as a whole can wasp-waist as much as you like — and the Shape tool turns a rough ring of taps into an exact circle, ellipse, rectangle or smoothed curve with typed dimensions. Loft has two join styles: Taper flows every layer into the next (vases, hourglasses), while Stand notices when a new layer sits inside the one below and keeps the big layer's top as a flat shelf — so a sculpture stands on its plinth instead of melting into it. And because slices are convex, islands need their own identity: that is what strand colours are for. Every colour is skinned as its own solid, so four small squares in four leg colours plus one slab in a fifth make a table — each leg rises straight to its matching colour above, ignoring its neighbours. Pick the Table starter to see all five strands at once, then Copy slice up keeps any of them growing.
Point budget: the hard limit is 2,000 points (drag and skin stay instant to there), but if the destination is scissors and cardboard, stay under 500 — skin triangles grow with points, and the hand-buildable tools cap at 800 faces for good reason. The Triangles readout above turns amber the moment you pass it.
XYZ to STL, without the CAD seat
Surveyors, drone mappers, lidar apps and 3D scanners all export the same humble format: a text file, three numbers per line. Turning that into a solid usually means installing CloudCompare or MeshLab and learning their reconstruction dialogs. For the common case — "just give me a watertight shape around these points" — the import button above does it in one step: files beyond 2,000 points are evenly subsampled, the cloud is auto-scaled into the metre cube, and the hull exports as STL. Your data never leaves the browser, which matters when the points are a client's site survey.
- Computational geometry — the convex hull as the unique minimal convex set containing a point set; Andrew's monotone chain for the per-slice 2D outlines
- Lofting — cross-section stacking from ship "lofting floors" to the loft operation in modern CAD packages
- ASCII XYZ / PTS point-cloud conventions — whitespace- or comma-delimited coordinates, one point per line
- Surface reconstruction literature — ambiguity of general reconstruction vs. the uniqueness of the hull