3D Slicer · Yepher

Notes

STEP export writes the visible parts as an AP214 solid that any CAD package opens. Coplanar triangles are merged into single planar faces with holes and straight, shared edges — a box becomes six faces on twelve edges — and faceted surfaces of revolution are recognised and written as true cylinders, cones, spheres and tori: holes and bosses, fillets, rounded corners, slots, D-flats, chamfers, countersinks, ball ends, rounded rims, pipe bends. Edges between them are exact where the geometry allows (circles, ellipses, rulings, seams) and cubic splines through the mesh vertices where it doesn't (a cross-drilled hole, a pipe tee, two spheres meeting), so meshes that went through a boolean convert too. Each part keeps its 3MF colour, and a report after the export scores how much of the surface came out as real geometry. Free-form and noisy surfaces stay faceted, one face per triangle; meshes that aren't watertight go out as a surface model rather than a solid. Files run to roughly 1 MB per 1,500 faceted triangles, so a dense scan makes a big STEP. For a big model with many parts, STEP assembly writes a zip instead: one STEP file per part under parts/ plus an assembly STEP that places them all by external reference (the AP214 pattern CATIA, NX and Open CASCADE use), so each part opens on its own and the whole is a fifth of the size.
Slice cuts the model with a plane at the middle of every layer. Pick X, Y or Z, or Custom to slice along any direction: press Pick a face and click a flat face in the 3D view to slice parallel to it, set the azimuth and tilt with the sliders (or type them), or orbit the 3D view to look straight along a feature and press Use camera direction. The slicer and joins the cuts into closed contours. Holes are wound the opposite way, so the area and volume figures subtract them. Export all layers as a tiled SVG for a laser-cut stack, or as a DXF with one named layer per slice. DXF · 3D stack writes the same outlines with each one lifted to its own height (DXF Z is the slicing axis), so CAD opens them as a stack of profiles you can loft between.
Laser-cut stack (Layers panel) turns the layers into cut-ready sheets: set the layer height to your stock thickness, give the beam kerf (parts are grown by half of it so they come out at size), a registration-hole diameter and count (holes are placed where they pass through every layer, as far apart as possible), and the stock sheet size. Parts are nested with etched layer numbers; SVG uses red for cuts and blue for etching, DXF uses CUT / HOLES / ETCH layers.
Send to Drawing (in the Layers panel) opens the Drawing Sheet with the visible parts, a hidden-line view looking along the slicing direction, the current layer's outline exactly as shown on the slice plane, and a section A-A cut at that layer, so you can dimension exactly the profile you set up here.
Drawing makes a hidden-line projection: silhouette edges, creases sharper than the angle you set, and open edges, with the parts hidden behind the model trimmed away. “Camera” projects exactly what the viewer shows; the named views assume the up axis you picked.
Binary and ASCII STL, 3MF, OBJ, PLY (ASCII or binary, with vertex colours), uncompressed glTF/GLB and FBX (ASCII or binary; the file’s unit setting is honoured) are read. A 3MF with several objects or parts (including Bambu Studio, Orca and PrusaSlicer projects, whose part names and filament colours are read) shows a Parts list with its colours; hide parts to slice or draw the rest on their own. 3MF units are converted to millimetres; STL is taken as millimetres; OBJ and PLY are guessed (metres when the model is under a couple of units across, otherwise millimetres) and glTF is metres. Use the File units control at the top if a model comes in the wrong size. Everything runs in your browser; the file is never uploaded. Very large meshes (millions of triangles) will take a while in Drawing mode.