It was finally done. They said it couldn't be done and yet, here it was. Donatello looked at his face in the cracked mirror that hung in the lab and smiled at the dark bags under his eyes and the soot on his face. He saw the machine working in the background and his heart swelled with pride. It was a point in history. There would be a little dot in future history books to remind people of this day.
"You actually did it?" Raph asked, leaning in the doorway, drinking a beer. "I thought you said it was impossible."
"I did," Don said, barely containing himself from hugging Raph.
His brother could sense his enthusiasm and took a step backward. "Great. What's it do?"
"Do? What do you mean? It's doing it now."
Raph's eyebrow ridges furrowed and he cautiously approached the machine and watched its belts and cogs working with no apparent output of any practical desired product. "This is it? This is the legendary machine that the alchemists couldn't make? They were a pretty stupid bunch weren't they, whining about how they couldn't make one of these things."
Don's pride was melting into annoyance. "The product isn't the point. It sustains itself by creating its own energy… You're right. It is kind of useless, isn't it?"
There was a crash in the living room. "Oops," said Mikey's voice. "I dropped your laptop, Don. Guess its dead."
That laptop held all of his important and irretrievable files. All of his blueprints for the machine were in their as well as his Bones fanfiction. There was only one choice. The machine must be sacrificed. The laptop was more important. It had a function. A purpose.
"Well, it was nice knowing you," Donatello said as he pulled away the energy source. The machine died. He knew that the laptop would live again.
Just for the record, Perpetual Motion Machines of the first kind are impossible. There's no way for a machine to create its own energy source without outside input. I don't know if Don would write fanfiction, but I have a feeling that if he did it would be really bad.