Sure, I can write a test case generator for the given problem statement "A Garden with Ponds". The generator will create multiple datasets where each dataset will have a grid with random elevations. Here is the Python code for generating the test cases:

```python
import random

def generate_test_case():
    d = random.randint(3, 10)
    w = random.randint(3, 10)
    
    elevation_grid = []
    for _ in range(d):
        row = [random.randint(0, 9) for _ in range(w)]
        elevation_grid.append(row)
    
    return d, w, elevation_grid

def tcgen(num_cases):
    cases = []
    for _ in range(num_cases):
        d, w, elevation_grid = generate_test_case()
        cases.append((d, w, elevation_grid))
    
    return cases

def print_cases(cases):
    for case in cases:
        d, w, elevation_grid = case
        print(f"{d} {w}")
        for row in elevation_grid:
            print(" ".join(map(str, row)))
    print("0 0")

# Generate 10 test cases
test_cases = tcgen(10)
print_cases(test_cases)
```

This code snippet does the following:

1. **generate_test_case()**: Generates a single test case by selecting random values for `d` and `w` (ranging from 3 to 10). It then constructs a grid of size `d`x`w` with random elevation values between 0 and 9.
2. **tcgen(num_cases)**: Generates the specified number of test cases by calling `generate_test_case()` and appending each result to a list.
3. **print_cases(cases)**: Prints all the test cases in the specified format, and adds the terminating line "0 0" at the end.

This approach ensures that each test case is randomly generated, adhering to the constraints provided in the problem statement.