While you can model heavy weld seams, bullet splash guards, or other cast tank and AFV details with styrene, there is another option: two-part epoxy putty. It’s easily activated and can be shaped into just about anything you’d need.
There are many kinds of two-part epoxy putty, like Tamiya’s Quick Type (No. 87051). They come with a resin and a hardener component, which are usually different colors. First, tear off equal amounts of both.

On a clean, hard surface, like a piece of tile, roll the two parts into tiny snakes equal in length and diameter. Work in small batches to both limit waste and maximize your working time before the putty dries.

Twist the snakes together and knead them until you get a uniform color. If you have sensitive skin, wear disposable gloves. The putty is sticky, so wet your fingers, tools, and work surface with water to prevent adhering.

When the combined putty mixture becomes a consistent single color, it’s ready to shape and attach to your model. For instance, to make cast bullet splash guards and welds for gun-tube sleeves, roll the combined putty into long ropes.

Cut the putty ropes to length and position them on the model with a metal or silicone-tipped shaping tool. Use water to prevent the putty from sticking to tools and work surface, but keep the model surface dry. That way the putty clings only to the model.

After the putty starts to firm up but is still pliable — about 30 minutes — refine the shape with metal tools suitable to the work. Here, a sewing pin chucked in a hobby knife handle adjusts the putty’s shape and adds smaller textural details.

By using both thinned putty and two-part epoxy putty (the black numbers and letters are dry transfers), you can create a more accurate replica of any AFV part, from this M10 gun mantlet to a Sherman tank turret and beyond.