Creating large, smooth surfaces in metal sculptures requires precision, the right tools, and expert techniques. Here are the most effective methods to achieve flawless results:

1. Welding and Grinding: Start by welding metal sheets or plates together, then use angle grinders with flap discs to smooth the seams. Progressive grits ensure a polished finish.

2. Planishing: Hammering the metal with a planishing hammer or pneumatic tool helps eliminate imperfections and creates an even surface.

3. Rolling and Pressing: Hydraulic rollers or presses can flatten large metal sheets uniformly, reducing the need for extensive manual smoothing.

4. Sandblasting: This technique removes oxidation and minor flaws while preparing the surface for further polishing or patination.

5. Hand Polishing: Using polishing wheels and compounds, artists can achieve a mirror-like finish on smaller sections or intricate details.

For durability, apply a clear coat or wax to protect the smooth surface from corrosion. Combining these methods ensures professional-quality results in large-scale metal sculptures.