After their incredible journey through time, Lily, Max, Ava, and Ben were inspired to create their own invention. They wanted to use their knowledge and skills to make a positive impact on the world.

They spent weeks brainstorming and experimenting in Max's garage. They tried out different ideas and prototypes, but nothing seemed to work. They were starting to feel discouraged, but they refused to give up.

One day, while they were taking a break and enjoying some snacks, Ava had a brilliant idea. She suggested combining their love for science with their passion for helping others. The friends were intrigued and asked her to explain.

Ava explained that they could create a machine that could turn trash into clean energy. They could use it to help reduce pollution and provide sustainable energy for communities in need. The friends were amazed by the idea and immediately got to work.

They used their knowledge of chemistry and engineering to design and build the machine. It was a complex process, but they worked together as a team and never gave up. Finally, after many trials and errors, their invention was complete.

They tested it out and it worked perfectly! They were able to turn trash into clean energy, just like Ava had envisioned. The friends were overjoyed and couldn't wait to share their invention with the world.

They decided to present their invention at the school's science fair. Everyone was impressed by their creation and they even won first place! Lily, Max, Ava, and Ben were proud of their accomplishment and knew that their invention would make a positive impact on the world.

Their invention was soon recognized by the local community and they were invited to present it at a sustainability conference. People from all over the world were amazed by their invention and wanted to implement it in their own communities.

The friends were thrilled to see their invention making a difference and they continued to work on improving it. They also continued to go on adventures through time, but now they had a greater purpose - to use their knowledge and skills to make the world a better place.

From that day on, Lily, Max, Ava, and Ben were not only known as the time travelers, but also as the inventors who changed the world. And they couldn't wait to see where their next adventure would take them. The end.