Case studies · 2 Oct 2026 · By Stefano B.

A STEP with no bill of materials: building it from the 3D

200 bodies, no parts list. Type, thickness and material read from the geometry, identical parts grouped: 198 parts became 139 drawings.

The customer sent a single STEP: 200 solid bodies named Solid1 to Solid200, and no bill of materials. No thicknesses, no materials, no quantities. Customer name removed; numbers measured on the delivered files.

1. Read every body

A script opens each body and decides what it is from the geometry. 200 bodies in 13 minutes, 0 errors:

Type	Bodies
Flat plates	170
Bent plates	6
Section profiles	9
Round bars	9
Blocks	2
Parts left to the designer	4

8 bodies the script could not classify with certainty were flagged and decided by the designer.

2. Thickness from the geometry

A STEP has no thickness field, so thickness is measured on each solid. The 9 section profiles were recognised from their shape. More in plate thickness from a STEP file.

3. Material from the colour

The model used two colours: 183 yellow bodies and 17 blue. Blue became stainless 316L, yellow carbon steel. The material went into the register, and from there into every drawing and booklet note.

4. Group identical parts

Many plates were the same part repeated. Parts are compared on their flat profiles with tight tolerances, and the designer approves each group on the 3D before anything is renumbered.

26 groups of identical parts
198 parts became 139 drawings, each with its quantity

5. Mirrored parts

The second assembly is the mirror of the first. A mirrored plate is the same part turned over, unless a bevel or a one-sided feature makes it different. Only those get their own left-hand (-SX) drawing. See mirrored left-hand parts.

The result

One register with code, type, thickness, material and quantity for every part. Drawings, booklet and nesting are all generated from it, so a quantity is written once and counted everywhere: 398 parts for two assemblies, checked against the register.