KLDraw is a KDE-compatible software for creating 3D LEGO models.
With KLDraw, you get some fantastic features which include: support for multipart models, a multi-document interface, and the ability to store part databases using SQLite (you'll need sqlite3 to compile). You can also raytrace models on-the-fly via POV-Ray (povray required).
To use KLDraw, you'll need the LDraw part library, which you can get from the LDraw site. Once you have it, simply install it in /usr/share/ldraw, and you'll be ready to start using KLDraw.
However, keep in mind that KLDraw is in the alpha stage. This means that there are many things yet to be implemented, although basic editing features are expected to work. If you find any bugs or have feature requests, don't hesitate to send them in. The KLDraw team is always welcoming patches and feedback.
Overall, if you're interested in creating 3D LEGO models, then KLDraw is definitely worth considering. Feel free to email the development team to learn more.
Version 0.1.0: N/A