Hint: Building materials
The answer to this puzzle is:
1. WOOD
2. BRICK
3. STRAW
4. STEEL
5. GLASS
6. STONE
7. CONCRETE
8. SAND
9. PLASTIC
10. TIN
11. MARBLE
2. BRICK
3. STRAW
4. STEEL
5. GLASS
6. STONE
7. CONCRETE
8. SAND
9. PLASTIC
10. TIN
11. MARBLE