Hope we will see what tools you use and how you operate. The feature on the Pulverizer had no images that show how the actual work is done.
Tools: Dentist tools, clay shapers, needles, toothpicks, files, knives, ... whatever works.
How to operate them: Carve, press, file, shape, push, drill, ... whatever works.
As with painting there are many ways to get specific results. To get a panel line on a flat piece of Green Stuff you could press the line into the putty while the putty is still soft, carve it out of the putty once it is cured, ...
A common method to get mechanical shapes like Mechs is to roughly shape the putty (using your fingers or clay shapers or whatever tool works for you) while it is soft, the, after the putty is cured, file, sand, carve, the shapes and angles you want, using the appropriate tools. To add detail, more layers of putty are added. But this is not the only way. As with painting, different sculptors have different ways to achieve similar results. As with painting, a lot is try/error and experience.
Basically, when not doing CAD work on a computer, you have a set of materials (two part epoxy like Green Stuff being the most common) and use whatever tools work for you to manipulate the putty/materials to take the desired shape. Work is usually done inside to outside.
