Did a 2007 mesh-to-solid plugin write a STEP file, or an ACIS solid?

Long before browser tabs ran a CAD kernel, the job of turning a triangle mesh back into something a CAD program could edit was sold as a desktop plug-in. The product page for one of those plug-ins was captured on 10 January 2007, and it lists its own input and output formats. That list answers this question without any guessing, and every number below is either read from that capture by the test suite or measured by this site.

The short answer

It wrote a solid, and STEP was not one of the formats it wrote. Mesh To Solid 3.0, captured on 10 January 2007, could read four mesh formats — Rhinoceros .3dm, 3D Studio .3ds, Stereolithography .stl and Wavefront .obj — and could save in exactly two: ACIS .sat and Rhinoceros .3dm. The number of STEP outputs on that page is zero. A single-user licence was 195 USD in 2007, and the trial ran for 10 days or a number of runs, whichever came first.

Read that as a dated fact about one product, not as a rule about every reverse tool. The page is the vendor’s own list of what its plug-in wrote; it is not evidence that ACIS was the only answer available in 2007, and it is certainly not evidence about what any tool writes today. The three-routes page covers the current market, including a free project that does write an editable STEP.

Four in, two out, zero STEP

What the captured product page lists, counted. The counts and the format names are read straight from the archived page by the test suite; the price is the 2007 figure printed there.
Item	Count	What the page lists
Mesh formats it could read	4	Rhinoceros `.3dm`, 3D Studio `.3ds`, Stereolithography `.stl`, Wavefront `.obj`
Solid formats it could save	2	ACIS files (`.sat`), Rhinoceros files (`.3dm`)
STEP outputs	0	No STEP writer appears anywhere on the page
Single-user licence, 2007	195 USD	Printed on the same page; a bulk-licence option was offered by contact only
Trial	10 days or runs	Whichever came first, and the trial was described as fully functional

The output list is the answer. The same page that offers four mesh inputs offers two solid outputs and names no STEP writer at all. That is the vendor’s list for that product, and it is the reason the question is worth asking: a plug-in whose entire purpose was turning a mesh into an editable solid still did not hand back a STEP file. The bottom half of the figure repeats the page’s own 195 USD licence and its 10-day or runs trial, both dated 2007.

Why the output list was short

The page does not hide the reason it existed. In its own description, general solid modelling software had no operations for editing mesh objects, while the operations people actually wanted — boolean add, subtract and intersect, extrude, offset, fillet, chamfer, rib, draft, shell — worked on solid or surface objects only. Its stated premise is that there was no way to turn a mesh into a solid, so the product was built to do exactly that.

Once a plugin is built around that premise, the output it can hand back is a boundary-representation solid, and the format list follows from whichever kernels the vendor chose to write. Here the choices were ACIS and Rhino. STEP is a neutral interchange format for exactly the kind of solid this product produced, so its absence is a product decision rather than a technical impossibility — but the page says nothing about why it was left out, and this page will not invent a reason.

The companion import plugin did not make solids either

The same vendor sold STL Import for AutoCAD 1.0, captured on the same day. It read the triangles in an STL and rebuilt the model as one of five AutoCAD object types: points, lines, polylines, 3D faces or a polyface mesh. None of those is a solid, which is consistent with the companion product: importing a mesh gave you something to look at and measure, and turning it into a solid was the separate purchase. It was priced at the same 195 USD for a single user, with the same 10-day or runs trial.

That split is the part worth keeping. In 2007 the market already distinguished “bring the mesh in” from “make it solid”, and the second step was the one with the price tag.

The dates behind the product

The vendor’s news list in the same capture gives three dated entries that bracket the product: 5 July 2006, the launch of Mesh To Solid for AutoCAD; 10 November 2006, the release of Mesh To Solid 3.0; and 21 November 2006, a dozen import and export add-ins for SolidWorks. The standalone 3.0 arrived four months after the AutoCAD add-on, and the same autumn produced a batch of SolidWorks plug-ins — a small vendor selling format bridges one CAD package at a time.

This site links none of those dates to a present-day product, because the vendor does not appear in today’s market and the page is a capture, not a shop.

The output list was a choice made inside a four-month window. Three dated entries from the vendor’s own news page sit within four months of each other, and the capture that lists the formats is dated 10 January 2007. Nineteen years later, in 2026, a free open-source project writes an editable STEP from mesh inputs — a different product, a different decade, and the format that the 2007 plug-in did not list.

What changed by 2026

Two things moved, and they did not move together. The output format changed: a free open-source project now writes an editable STEP from mesh inputs, which the three-routes page covers with its published price of zero. The price also changed: the same work is now sold as credit at about $0.83 a conversion or as an engineer’s time from as low as $150 a file in a 2020 capture. Neither change makes an STL into a STEP by itself; the reverse-direction page owns why the result is a reconstruction, and the rebuild page owns how that reconstruction is done.

What did not change is the thing this page is about. Whichever format a tool writes, it is writing a new solid over the triangles, not recovering one. The 2007 page made that visible by naming its two output containers; a modern tool hides the same step behind a STEP extension.

What this site does

The converter on the front page reads STEP and IGES files and writes STL, one direction only, with coordinates in millimetres and the axes unchanged. It runs in the tab: the kernel is a 7,604,031-byte WebAssembly file fetched from this site’s own folder, and the file you open is never uploaded. The measurements are re-run by the test suite — the flat 10 mm cube is 12 triangles and 684 bytes at every quality setting, and an 18-part assembly of 433,606 bytes comes back as 7,372 triangles in a 368,684-byte STL at Normal. Those numbers describe the forward direction only; no reverse conversion is offered here at any price.

Questions this page answers

Did Mesh To Solid write STEP files?

No. The product page captured on 10 January 2007 lists exactly two output formats for Mesh To Solid 3.0, ACIS files (*.sat) and Rhinoceros files (*.3dm). A STEP writer is not on that list, so the count of STEP outputs is zero. The list is the vendor's own statement about that one product, not a claim about every reverse-engineering tool of the period.

What could a mesh-to-solid plugin write in 2007?

Two solid formats, according to the same page: ACIS .sat and Rhinoceros .3dm. On the input side it read four mesh formats, Rhinoceros .3dm, 3D Studio .3ds, STL and Wavefront .obj. The product's purpose was to turn a mesh into a solid so that solid modelling operations could be run on it; the format it handed back was a boundary-representation solid in one of those two containers.

What did it cost, and is that price current?

The captured page prices Mesh To Solid at 195 USD for a single-user licence, with a trial of 10 days or a number of runs, whichever came first. That is a 2007 price on a product page from a vendor that no longer sells it, and it says nothing about what any tool costs today. This page prints it as a dated fact, not as a market rate.

Does this site convert an STL into a STEP file?

No. The converter here reads STEP and IGES files and writes STL, one direction only, with coordinates in millimetres and the axes unchanged. It will not take an STL as input, it sells no reconstruction, and the historical products on this page are not offered here in any form. The format list this site accepts belongs to the verification page and is not repeated on this page.

Where these numbers come from

Mesh To Solid 3.0, four input formats, two output formats, no STEP writer, 195 USD, 10-day or runs trial — a Wayback Machine capture of the Sycode product page dated 10 January 2007, kept in this project’s research folder as sycode-mesh-to-solid-20070110.html. The test suite reads that file directly, counts the format lists and requires this page to print the same counts. The capture predates 2023 and the domain is no longer live.
STL Import for AutoCAD 1.0, five rebuilt object types — the companion product page from the same capture, kept as sycode-stl-import-20070110.html, also priced at 195 USD with the same trial terms.
5 July 2006, 10 November 2006, 21 November 2006 — the dated news entries in the vendor’s site capture, kept as sycode-20070110.html. Dates are printed as the page printed them.
7,604,031 bytes, 12 triangles / 684 bytes, 433,606 bytes → 7,372 triangles → 368,684 bytes — the kernel file’s length on disk and this project’s own measured conversions, re-run by npm test on every release. They describe the forward direction only.
What this page does not print — no monthly search volume, no keyword bid, no current price for any tool, and no claim that the 2007 product or its formats are available here. The only price is the 2007 one, with its date. The verification page owns the format rejection list; this page links to it rather than repeating it.

npm test

The command above re-runs every number this project measured. The reverse-direction page owns whether STL to STEP is a conversion at all; the rebuild page owns the method; the three-routes page owns today’s market and its prices; and the converter is where a STEP file meets the kernel, for free, in the tab.