What Is True-Shape Nesting? (And When It Saves Material)

True-shape nesting arranges parts on a sheet or roll by their actual outlines, so curved and irregular parts can tuck into each other's concave areas. Rectangular (bounding-box) nesting treats every part as the smallest rectangle that encloses it, which is exact for rectangles but wastes the space around curves, corners and cut-outs.

Laser, plasma, waterjet, router and knife cutters can follow any path, so they can take advantage of true-shape layouts. A panel saw can't: it needs edge-to-edge cuts, which is why saw layouts stay rectangular.

Fitting irregular shapes together is a hard geometric search problem, so every nester is a heuristic: it finds a good layout, not a proven best one. Three approaches are common:

• No-fit polygons with bottom-left placement. For each pair of parts the software computes where one can sit against the other without overlapping, then places parts one at a time as far down and left as they fit, trying many part orders. Deepnest and SVGnest work this way, with a genetic algorithm shuffling the order and rotations.
• Overlap minimisation. The newer approach squeezes the layout smaller than it can really be, then nudges parts until no two overlap, and repeats. sparrow (KU Leuven, open source, 2025) uses this, and it beats the older methods on the standard academic benchmarks. EZNESTING's true-shape engine is built on it.
• Raster (pixel) grids. Parts are turned into pixel masks and tested for overlap. It's simple and robust, but only as accurate as the grid.

Because it's a search, more time usually means a tighter layout, with diminishing returns. That's why some tools let you keep searching, and why a true-shape nest takes seconds where a rectangular one is instant.

We ran the same parts through EZNESTING twice: once nesting bounding boxes, once true-shape.

Curved upholstery panels on a 54" roll (12 seat tops 20" × 17.2", 24 side panels 24" × 7.76", 1/16" spacing):

That's 22% less fabric, because the curved panels interlock.

Signs on a 4×8 sheet (15 round 10", 10 arch-top 12" × 18", 10 hexagons 8" across flats, ¼" spacing):

Here it saved a whole sheet, but that job sat right at the edge of one sheet. On slightly different quantities both methods needed two sheets, and true-shape only packed the first one 4 to 10 points fuller.

The pattern: the more concave and irregular the parts, the bigger the gain. Circles and hexagons gain a little (they can't interlock much). Rectangles gain nothing. Arches, wedges, brackets and pattern pieces gain the most.

• Part spacing. The minimum gap between outlines. Set it to what your machine removes plus a margin: about the bit diameter on a router, kerf plus a little on a laser or plasma, close to zero on a knife table.
• Rotation. More allowed angles usually means a tighter nest. Parts with grain or a print direction should be limited to half turns (0° and 180°), so they never cross the grain.
• Mirroring. Some tools can flip parts. Leave it off for left- and right-hand parts that must stay different.
• Parts in holes. Some nesters place small parts inside the cut-outs of big ones. It matters for gaskets and flanges; most parts don't have holes big enough to use.
• Sheet or roll. A sheet has a fixed size; a roll has a fixed width and the goal is the shortest length.
• Search time. Longer searches find tighter layouts, with diminishing returns.

1. Open the nesting optimizer with a 4×8 sheet loaded. No account needed.
2. Click Import parts and choose CAD drawing (DXF). Lines, arcs, splines and blocks are read; notches and holes stay with their part.
3. Set quantities, spacing (kerf) and grain, then optimize. Shaped parts nest by their outlines automatically.
4. Use Keep improving to search longer, then export DXF for your CAM.

The free plan covers up to 5 part sizes and 3 stock sizes per job, with DXF export included. More detail on the importer and exports is on the DXF nesting page.