The manuscript by Wang and co-authors presents G&M3D, a software package with a graphical user interface to create a set of three-dimensional subsurface bodies. The bodies are either based on basic geometric shapes or freely drawn with the mouse on individual profiles and then combined into a 3D volume. The software furthermore allows the user to assign density differences and magnetic properties to the bodies and forward model the resulting gravity anomalies and magnetic intensity as well as their gradients. The authors demonstrate the software’s capabilities in an application to the gravity anomaly caused by a real salt dome. The manuscript is well written, the text is clear in most places, and the content fits the scope of GMD. The Figures nicely illustrate how the graphical user interface looks and can be used.

There are some concerns/open questions regarding the flexibility and efficiency of the method, the accessibility of the software, and the clarity of the text. These can be addressed with moderate revisions. Please see the attached PDF for my comments.

I have read and reviewed the manuscript entitled “G&M3D 1.0: an Interactive Framework for 3D Model Construction and Forward Calculation of Potential Fields.” The paper addresses an important and practical challenge in the potential-field community, namely the construction of realistic and geologically meaningful 3-D synthetic models. From both technical and implementation perspectives, the manuscript is generally well structured and in good shape. I therefore recommend minor revision. My moderate-level comments are listed below.

-Software design philosophy and architectural principles

As the manuscript presents a scientific software framework, it would be beneficial to more clearly describe the underlying software design philosophy and architectural principles adopted in the development of G&M3D. For example, discussing aspects such as modularity, low coupling and high cohesion, extensibility, and the separation between data structures and computational kernels would help readers better understand the robustness, scalability, and long-term maintainability of the framework.

-Input/output specifications and data interoperability

The paper would benefit from a clearer description of input and output requirements. In particular, it would be useful to specify supported data formats, model parameterization conventions (e.g., coordinate systems and right-hand rule definitions. A brief discussion on interoperability with existing modelling or inversion workflows (e.g., UBC-GIF formats, SEG standards, Oasis Montaj, etc) would further enhance the practical value and adoption potential of the framework.

-Representation of heterogeneous physical properties

In the current implementation, each geological body appears to be assigned a constant physical property. The authors are encouraged to discuss the spatially varying physical properties, for example, Gaussian distribution.