Stabilizing a porcelain sculpture with an unstable or uneven base requires careful attention to preserve its integrity and aesthetic appeal. Here are the most effective methods to achieve balance and support:

1. Use a Weighted Base Plate: Attach a flat, heavy plate (such as metal or stone) to the bottom of the sculpture to lower its center of gravity and prevent tipping.

2. Adjust with Shims or Wedges: Insert small, discreet shims or wedges beneath the base to level the sculpture. These can be made of wood, rubber, or felt to avoid scratching surfaces.

3. Apply Adhesive Putty or Museum Gel: For temporary stabilization, use non-damaging adhesive putty or museum gel to secure the sculpture to its display surface.

4. Custom-Made Stand or Mount: Consult a professional to create a custom stand or mount tailored to the sculpture’s shape and weight distribution for long-term stability.

5. Reinforce with Epoxy or Resin: For cracked or fragile bases, carefully apply epoxy or resin to strengthen the structure while maintaining its appearance.

6. Sand the Base Evenly: If the unevenness is minor, gently sand the base with fine-grit sandpaper to create a flatter surface.

Always handle porcelain sculptures with care and test stabilization methods in a discreet area first. For valuable or antique pieces, seek advice from a professional conservator to avoid irreversible damage.