Blender has introduced NURBS!

This model was made using NURBS surfaces in Blender. To create it, I used an add-on called Surface Psycho, which you can download right from the preferences.
It's not a typical CAD software, so it's not exactly easy to use, but it lets you model hulls pretty efficiently.
With the add-on you can import and export IGES and STEP file

here the link to the add-on extension:
Surface Psycho https://extensions.blender.org/add-ons/surfacepsycho/

I'm learning this new tools, I'm still a newbie.

Time to time I will share here what i can.


Cheers

 

Very nice!
IGES>Rhino (make X=long ways and split in half)>VRML1.0>Delftship Free with creasing added to transom

 

Hey everyone, I'm sharing another slightly more complete model that helped me learn even more about this Blender add-on. It took a fair bit of effort and time, models like this would require way less work in apps like Rhino or other CAD software. Plus, the Blender add-on is designed for surfacing and isn't really suited for stuff like solid part modeling; it doesn't support boolean operations, for example. Here you're working at a lower level, with control vertices and NURBS/Bézier patches. Pretty much everything has to be built that way. There are a few tools to create basic objects like cylinders or other simple shapes, but that's not the main goal of this add-on, it's aiming to become a proper Class A surface modeler.

The attached STEP and IGES files open without issues in FreeCAD, though I've had some trouble with other programs. That said, if you don't want to download FreeCAD, there's an open-source viewer called Mayo that handles various CAD formats really well and opens these files perfectly, both apps use the Open Cascade libraries, after all.

The Blender model itself opens in Blender 5.0, but if you want to export it to STEP or IGES, you'll need to install the add-on.

I've done some more complex stuff too, but for now they're just experiments that helped me understand what this tool can really do.

I don't want to get anyone's hopes up by saying this will solve all your modeling problems, sometimes it's worth spending a few bucks on dedicated software. But if you're up for learning something new, roll up your sleeves and dive in, because there will definitely be some challenges along the way!
Greetings and happy new year!

 

Blender has endless possibilities when it comes to managing viewports with the new Geometry Nodes tools. Plus, the object color feature, which I'd never really used before, turns out to be super useful in CAD projects. With Surface Psycho and the JLB SurfAce add-on for surface analysis, it's now a proper advanced surface modeler, being able to analyze hulls in real time with instant feedback on changes makes it a powerful tool for hull design.



Greetings

 

A 3D hull model more complex than the previous ones, but it's not perfect.

 

Convert Subdivision Surfaces to NURBS with Surface Psycho – Beginner Guide​

Surface Psycho is a free Blender add-on that converts subdivision surface models into NURBS surfaces without leaving Blender. It’s ideal if you later want to export your model as a CAD file (STEP or IGES).
The process is a bit slow on complex models, but it delivers very good results.

Step 1 – Install the add‑on

1. Open Blender and go to Edit > Preferences.
2. Select the Extensions tab.
3. In the search box, type Surface Psycho.
4. Click Install next to the add‑on.

Step 2 – Set the asset path
After installation, you must tell Blender where to store the assets:

• Go to Edit > Preferences > Add-ons.
• Under Surface Psycho > Preferences, press button Add Asset Path. This step is required for the add‑on to work correctly. There are also other buttons for Psycho Matcaps but is optional.

Step 3 – Add the geometry nodes to your model
Select the object you want to convert.

1. Go to the Modifier Properties tab (wrench icon).
2. Click Add Modifier and choose Geometry Nodes.
3. From the node group list, pick SP – SubD to Compound (add this first).
4. Add a second Geometry Nodes modifier and this time choose SP – Compound Meshing.

The order matters – always put SubD to Compound before Compound Meshing.

Step 4 – Choose the face type
Inside the first modifier (SP – SubD to Compound), you’ll find a Face Type setting.

• Bezier – works, but surfaces may be less smooth.
• NURBS – gives noticeably better surface quality and very good continuity (recommended).

Step 5 – Use Edge Crease (optional)
If your original model uses Blender’s Edge Crease to keep some edges sharp, Surface Psycho will respect that. Not all conversion tools support this.

Step 6 – Export to CAD format
When your model isn’t extremely complex, you can export it directly:

• File > Export > STEP or IGES. The NURBS data is saved, ready for other CAD software.

Step 7 – Explode the compound (advanced)
You can “explode” the generated compound mesh into individual NURBS surfaces. This lets you rework each surface separately inside Blender.
(Exploding means applying the modifier and separating the pieces – the exact method depends on your version, but the add‑on makes it possible.)

Note – The add‑on is free and works well, but small imperfections can appear in tight corners. Overall, it’s one of the best free solutions for converting SubD models to NURBS inside Blender.

Some sample images







Greetings