FreeCAD

To fuse solids together it is better to have overlapping solids.

Part Design modelling has a sequential workflow, the operations are piled one after another (except for sketches which are nested inside their operation).

Sketches are automatically hidden after use in an operation.

Part modelling has a hierarchal workflow where instances are nested into each other after operations.

Sketches are not hidden after use in an operation.

A useful tool to inspect how many solids compose a single document.

The dependency graph depends on the GraphViz library.

On major linux distribs you can simply install graphviz from the repos :

$ sudo apt install graphviz

If FreeCAD signals that it cannot find the GraphViz package when you are sure it is installed, you can correct this by pointing it to /usr/bin/ with the appropriate dialog box.