The idyllic island of Draco’s Bay, with its towering copper structures and winding cogs, was a haven for inventors and adventurers. Young Eli with his keen eyes and nimble fingers was no exception. His grandfather, old Percival, taught him everything about the intricate-mechanical devices that powered their home.

Percival was a renowned inventor himself, and the lighthouse he designed was an embodiment of his genius. It was not just a beacon for ships but also a mysterious trove of his inventions. Eli would spend hours exploring its secrets.

One day, Percival disappeared. The villagers searched the entire island but found no trace of him. The lighthouse, once a symbol of hope, now stood as a poignant reminder of his absence.

Days turned into weeks, and hope started to dwindle. But Eli, determined not to give up, decided to take matters into his own hands. He made a solemn vow to find his grandfather, no matter what it took.

Armed with a small rucksack filled with tools and a heart filled with courage, Eli set off. His first point of call was the lighthouse, the heart of his grandfather's endeavours.

As the lighthouse door creaked open, the familiar smell of oil and brass greeted him. Eli carefully moved around, examining every device, every blueprint, searching for any clues.

In the attic, he discovered a curious cog he had never seen before. It was larger than usual, adorned with peculiar symbols. An elaborate map of islands was etched onto its surface, some of them uncharted.

Eli was a born tinkerer and thus, he knew what he had found. It was not just a cog, but a cryptex, a secret container that his grandfather often used to hide important things.

He spent days trying to unlock this mysterious device. He was almost about to give up when he noticed something. A pattern. The symbols matched the constellations in the sky.

Using his knowledge of the stars, he finally managed to unlock the cryptex. Inside, he found a note from his grandfather, "Seek the island where the sun meets the sea."

Eli was puzzled. But remembering his grandfather’s tales about the horizon, he realized the message referred to the far western island where the sun sets – the uncharted land on the cog's map.

The journey was risky, dangerous. The island sat amidst treacherous waters and unscalable cliffs. But the thought of finding his grandfather overpowered any fear. He was ready to embark on this journey.

He prepared a steam vessel, filled with supplies for his search. The villagers, inspired by his determination, contributed whatever they could to his cause. Eli was not alone in this quest.

As he set off, the islanders cheered him on. He looked at the lighthouse one last time, the beacon of hope now ignited within him, guiding him towards the unknown.

The journey was fraught with unknown perils. But Eli’s ingenuity and his grandfather’s teachings helped him navigate the treacherous seas, dangerous creatures, and uncanny storms. He pressed on, undeterred.

Finally, after what felt like an eternity, he spotted land. The island where the sun meets the sea. As the vessel edged closer, his heart pounded louder. He knew he was nearing the end of his search.

He stepped onto the island, a strange mix of hope and anxiety filling him. It was a place unlike any he had seen – full of peculiar mechanical contraptions similar to those his grandfather would invent.

As he ventured deeper into the island, he found a hidden cave that held the proof he needed. Percival’s tools, blueprints, even his half-eaten sandwich. His grandfather was here and he was close.

Suddenly, the ground beneath him reverberated. A hidden door emerged within the cave. Eli hesitated, then resolute, stepped forward and pushed open the door. The sight that met his eyes left him in awe.

Beneath the island, lay a world alive with mechanical marvels. Machines whispering stories of innovation and progress. And in the midst of it all, was his grandfather, Percival, hunched over an amazing contraption.

Eli always knew his grandfather was a great inventor, but this was beyond everything he had ever imagined. He was creating a world of machines that co-existed harmoniously with nature, a utopia of sorts.

Percival, surprised and delighted, welcomed Eli warmly. He explained that he had not disappeared; he was just working on his greatest invention. "A place where the machine and nature can coexist in harmony," he said.

Eli was filled with joy and relief. He had found his grandfather, and he had discovered that the spirit of invention was more than gears and cogs; it was about creating a better world.

Together, they worked on enhancing the mechanical paradise, learning from each other. Eli was no longer a mere apprentice, but an inventor in his own right. He had truly found his purpose.

Once their work was complete, they returned to Draco's Bay. The villagers were overjoyed to see Percival again and amazed to learn about the hidden world. The lighthouse was no longer a symbol of loss, but a beacon heralding a new era.

Eli's adventure taught him resilience and determination. It forged a stronger bond between him and his grandfather. But most importantly, it taught him the true essence of innovation and progress.

The legacy of Percival will continue to shine in Draco's Bay. But more than the lighthouse or his inventions, it was the spirit of curiosity and the constant pursuit of innovation that was his true gift to Eli and the island. And this gift, like the steady glow of the lighthouse, will guide them towards an ever-brightening future.