# Edit Your Existing STEP Files with the Flux Agent Upload a STEP, IGES, or BREP file to Flux. The agent rebuilds it as editable CAD code, makes your change, saves it as a new model, keeps the original unchanged, and checks the result. Written by [Matthias Wagner](https://flux.seobdtools.com/natarius) Published Oct 2026 - 4 min read ![Edit Your Existing STEP Files with the Flux Agent](https://flux.seobdtools.com/p/assets/blogs/edit-imported-step-files/main.webp) Most mechanical work starts from a part that already exists. A supplier sends a STEP file. A colleague exports an enclosure from SolidWorks. A design from last year needs one more connector. The Flux agent can edit these files, not only the models that it made itself. You upload the file and say what to change. The agent makes the change, saves it as a new model, and keeps your original file unchanged. ## Files you can edit You can upload these CAD formats to a Flux project: - **STEP** (`.step`, `.stp`, and compressed `.stpz`) - **IGES** (`.iges`, `.igs`) - **BREP** (`.brep`) These are exact CAD formats. They keep the faces, edges, and dimensions of the part, so the agent can measure the part and rebuild it accurately. Assemblies are also supported. Flux keeps each unique part, its placement, its color, and its repeated instances. ## How the agent edits an imported part 1. **Measure.** The agent reads the size, the solids, and the features of the original file. 2. **Convert.** The agent rebuilds the part as editable CAD code. The code has named values, for example the length, the wall thickness, and the hole positions. 3. **Compare.** The agent compares the generated code with the original geometry. It uses the code only when the two match. 4. **Edit.** The agent changes the named values. If a part does not convert accurately, the agent imports the original geometry into the code and edits on top of it. 5. **Save a new model.** The result is a new code model in the project. The original file stays in the project, unchanged. 6. **Verify.** The agent measures the new model and checks it against the change that you asked for. ## Example: make a sheet-metal power supply holder fit a taller power supply We uploaded a bent sheet-metal holder that covers a power supply. It is an open-source STEP file, exported from Autodesk Inventor. We gave the agent this request: > "We changed to a power supply that is 40 mm taller, and this holder must still cover it and keep it cool. Change the holder so it covers the new power supply and lets air through. Keep the mounting hole in the flange where it is, so the holder still fits the machine." The agent made the bent flange 40 mm deeper and added 8 vent slots. It kept the 4.4 mm mounting hole in the same place. It saved a new STEP file and editable CAD code. The original file stays unchanged. ![Flux 3D View: the original sheet-metal power supply holder, and the revision with a 40 mm deeper bent flange and vent slots](https://flux.seobdtools.com/p/assets/blogs/edit-imported-step-files/main.webp) The original holder (left) and the agent's revision (right). ## Example: make a SolidWorks enclosure 20 mm longer We uploaded the bottom half of a sensor enclosure. It is a real STEP file, exported from SolidWorks. We gave the agent one request: > "This is the bottom half of our sensor enclosure, exported from SolidWorks. Make it 20 mm longer so a bigger battery fits. Keep the wall thickness, the corner radii and the mounting holes the same. Keep my original STEP file unchanged." The agent measured the part: 100 × 55 × 23 mm, with 3 mm walls. Before it made the edit, it asked one question. The request did not say if the end mounting holes stay in place or move with the longer end. ![Flux chat: the uploaded STEP enclosure, the agent's measurement of 100 by 55 by 23 mm, and a question with two choices, keep all mounting-hole positions fixed or move the end holes with the extended end](https://flux.seobdtools.com/p/assets/blogs/edit-imported-step-files/agent-question.webp) We chose to move the end holes with the extended end. The agent rebuilt the part as editable CAD code with named values, set the length to 120 mm, and saved the result as a new model. The image below shows the original part (back) and the 120 mm revision (front) in the 3D View. ![Flux 3D View with the original 100 mm sensor enclosure bottom in the back and the 120 mm revision in the front, with the same walls, battery shelf and mounting bosses](https://flux.seobdtools.com/p/assets/blogs/edit-imported-step-files/side-by-side.webp) ## What the agent checked The agent wrote a verification report to the project files. We also downloaded both models and measured them ourselves. The results: - The revision measures 120 × 55 × 23 mm. The width and the height did not change. - The agent did not scale the part. The walls, the corner radii, and the hole sizes did not change. - The end mounting holes moved by exactly 20 mm. The holes and bosses on the other end did not move. - The original STEP file is byte-for-byte the same as before the edit. ![Flux Files tab with the verification report next to the original STEP file and the new 120 mm model](https://flux.seobdtools.com/p/assets/blogs/edit-imported-step-files/verification-report.webp) The report also says what it did not check. It checks the dimensional change. It does not check that the bigger battery or the lid fits. Check those before you make the part. ## Why editable code is important An imported STEP file is a dead shape. It has faces and edges, but no design intent. When the agent rebuilds the part as code with named values, the next change is easy. You can ask for another 5 mm, a thinner wall, or one more mounting hole, and the agent changes one value instead of the full shape. Each revision is a separate model, so you can compare it with the original at any time. ## Prompts to try - "Make this enclosure 10 mm taller, and keep the lid interface the same." - "Add a 12 mm cutout for a USB-C connector in the short wall, centered 6 mm above the floor." - "Change the wall thickness of this housing from 2.5 mm to 2 mm, and keep the outside dimensions." - "Move the four mounting holes of this bracket to a 40 × 40 mm pattern." Open a project in [Flux](https://flux.seobdtools.com/), upload a STEP, IGES, or BREP file, and tell the agent what to change. ## About the author [Matthias Wagner](https://flux.seobdtools.com/natarius) Founder & CEO at Flux Matthias is the Founder and CEO of Flux, a hardware design platform that's revolutionizing how teams create and iterate on circuits. Find him on Flux [@natarius](https://flux.seobdtools.com/natarius). Let’s start building Build your big idea together with Flux. All you need to do is describe what you want to make, or what problem you want to solve. Flux will work with you to make it a reality. ![Close-up photo of a PCB made with Flux, with an ESP32 module, buttons, and a microSD slot.](https://flux.seobdtools.com/p/assets/blogs/miscellaneous/sidebar-cta-pcb.webp) [Try it Free](https://flux.seobdtools.com/signup) ## Related Content [ ![Teal technical illustration of a circuit board and enclosure with hand-drawn circles and arrows](https://flux.seobdtools.com/p/assets/blogs/markup-mode/main.webp) ### Circle it. Ask Flux. 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All you need to do is describe what you want to make, or what problem you want to solve. Flux will work with you to make it a reality. [Try it Free](https://flux.seobdtools.com/signup) ![Close-up of a Flux-designed printed circuit board](https://flux.seobdtools.com/p/assets/homepage-v2/mission-visual.webp)