Chen Hao slammed the pen into the whiteboard tray, turned, and walked back to the control panel. His finger touched the power button, then he pulled it back.

The machine is still on, the screen is black, but the cooling fan is still spinning.

He didn't press it again.

"Take a break," he said. "My eyes are practically shooting sparks from staring at you."

Susan leaned against the wall, rubbing her temples. She had been staring at the oven panel, and now her vision was still blurry. She blinked a few times before her vision cleared a little.

"I'm going out for some fresh air."

No one stopped her. The air in the workshop was stuffy and heavy, mixed with the smell of heated metal; inhaling too much of it would make your head throb.

She pushed open the side door and went outside. The wind wasn't strong, and it was still dark; the perimeter lights of the base cast a yellowish glow. She walked slowly along the base of the wall, her footsteps making a soft sound on the gravel.

When she reached the third supporting pillar, she saw the plant.

It grew along a crack in the wall, its stem slender and long, with a slightly bent tip, as if it had been pressed down by the wind for a long time. She squatted down to look at it and casually tore off a piece.

The sound of the stem breaking was crisp, but effortless. She held it in her hand and examined it, finding that the outer skin was hard, the inside was hollow, and the fibers were layered, like a twisted hemp rope.

She tried to bend it, and the stem bent so much that it almost touched her, but it bounced back immediately when she let go.

No way.

She glanced at it a couple more times.

When I stood up and started walking back, I quickened my pace.

The three were still in the same spot in the workshop. Karl sat on a small stool counting bolts, arranging them one by one in a row. Nana stood in front of the terminal, the optical lens pointed at the main control screen, seemingly waiting for instructions. Chen Hao lay face down on the table, whether asleep or playing dead, it was unclear.

As soon as the door opened, everyone looked up.

Susan walked directly to the workbench and placed the plant on the metal plate.

“This,” she said, “take a look.”

Chen Hao propped himself up, squinted, and leaned closer. "Weeds?"

“No.” She picked up the broken part with tweezers. “Look inside, it’s layered, hard on the outside and soft on the inside. I just tried it, it didn’t crack even when bent to that extent, and it bounced back when I let go.”

Nana reached out and took the sample, her mechanical fingers gently pinching both ends and mimicking a bending motion. Her database began scanning the internal structure.

"A spiral fiber arrangement was detected, and the stress distribution showed a gradient change," she said. "The surface layer has high tensile strength, and the inner core has elastic recovery capabilities."

“That sounds like what we need.” Carl put down the bolts and came over. “The transmission rod needs to withstand impacts and be resilient; it can’t break at the slightest touch.”

“The problem is that this is a plant,” Chen Hao said, stroking his chin. “We’re making metal parts.”

“But the principle is the same.” Susan pointed to the cross-section. “Why can it do that? Because different parts are made of different materials. Can we also make different areas of the material have different properties?”

The room was silent for a second.

"You mean... partial treatment?" Chen Hao asked.

“Yes.” She nodded. “Don’t heat the whole board uniformly. Harden the areas under heavy stress, and leave some flexibility in the connecting areas. Just like this stem, hard skin and soft core.”

Chen Hao looked at Nana. "Is it possible?"

Nana has already brought up the alloy lattice model and is comparing it with the orientation of plant fibers. "It's theoretically feasible. By heating in sections and controlling the crystal growth direction and density in different regions, we can simulate gradient structures."

“That sounds pretty far-fetched,” Carl said, scratching his head. “But do we have that capability? Our equipment isn’t a laser engraving machine.”

“No fine-tuning is needed,” Nana said. “As long as you can apply targeted heat to key areas and maintain a time difference, you can create a performance difference.”

Chen Hao walked half a circle around the workbench and then suddenly stopped.

"In other words, we don't need to strive for perfection in the entire material. As long as the key parts meet the standards, the rest can be made do?"

“That’s right,” Nana confirmed.

“Then we’ve been doing it all backwards.” He chuckled. “We’ve been looking for a universal temperature that can make the whole board stronger without making it brittle. Turns out, such a temperature doesn’t exist.”

“It exists,” Susan corrected, “but not on the same plane.”

"So what do we do now?" Carl asked, "Burn them one by one with a blowtorch?"

“We can use a heat-insulating coating,” Nana suggested. “It can cover non-target areas and concentrate the heating on key parts.”

“I’ll draw the area.” Susan picked up a marker. “Based on the design drawings, mark the points of greatest stress.”

She bent down and drew lines on the metal plate with swift, deft movements. Chen Hao watched from the side and suddenly felt a little relieved.

The problem isn't solved, it's changed.

Previously, they were stuck on "how to make this board obey," but now it has become "how to make one part obey and the other part cause less trouble."

The difficulty level has been reduced by more than one level.

"And the heating sequence?" he asked.

"First, preheat the whole thing at a low temperature to release initial stress," Nana said. "Then heat it up in stages, and finally cool it down slowly to avoid thermal shock."

“It sounds like a steak,” Carl said. “Crispy on the outside, tender on the inside.”

"Pretty much," Susan laughed, "except we don't eat this piece of meat."

"What a pity," Carl sighed. "Otherwise, we could have added some spice."

Chen Hao sat back in his chair and pulled a new notebook from the drawer. The cover read "Spare Log." He tore off the first two blank pages and began writing titles.

"What should we call it this time?"

“It’s called the ‘Don’t Burn the Pole Off Course’ plan,” Carl said.

"Too long." Chen Hao shook his head. "It's called 'segmented roasting'."

"Ugly," Susan said, pursing her lips.

"Down-to-earth." He didn't seem to care. "The name doesn't matter, as long as it works."

Nana has started programming. Her robotic arm connects to the debugging interface, and a new process pops up on the screen: preheating → shielding → targeted heating → heat preservation → natural cooling.

“Three temperature points need to be monitored manually,” she said. “The infrared thermometer can only be fixed at two locations, and the third needs to be manually added.”

“I’ll do it,” Carl raised his hand. “I don’t touch heavy things anyway.”

"You're in charge of reading the numbers, don't doze off." Chen Hao handed him the record sheet. "Last time you got the current value wrong, which made me wrap the wire three extra times."

“That time it was because the lights were glaring,” Carl muttered.

“The light is brighter this time.” Susan moved the lamp to a different angle. “Let’s see where you push it.”

"How do we set the heating time?" Chen Hao asked Nana.

"The initial plan is for each stage to last five minutes, which will be adjusted based on real-time feedback."

“Then let’s try a small piece first,” he said. “Let’s practice with the scraps.”

Susan picked out a scrap piece from the waste pile, large enough for one test. She fixed it to the experimental frame, coated both sides with a high-temperature resistant paint, leaving only the middle section exposed.

"This is the area that needs to be strengthened," she pointed out to Nana.

Nana nodded, and her mechanical fingers picked up the infrared probe and calibrated its position.

"Preparing to start the program."

"Wait a minute." Chen Hao stood up. "Who will close the door? The temperature will get unstable if the wind blows."

Carl ran to close the door. Susan checked the insulation to make sure it was intact. Nana confirmed the system was working correctly.

Chen Hao took one last look around.

"Let's begin."

Nana pressed the start button.

The machine hummed again. The heating element gradually turned red, and the heat concentrated on that small section of metal.

Time passed second by second.

Phase 1 is complete; now it enters shielded heating phase.

Karl reported three temperature values, all of which were within the acceptable range.

The second phase begins.

The color of the metal surface changed slightly, with the edges turning a dark yellow.

"Looks... alright?" Susan stared at the observation window.

"There are no abnormalities at present," Nana said. "The crystal recombination process is normal."

The third phase is about to begin.

"Are you ready for the temperature drop?" Chen Hao asked.

"The fan is in place, and the natural cooling process is ready."

"Then let's continue."

Nana inputs the command.

The heating head slowly approaches the target area.

Suddenly, the alarm went off from the left-side security camera.

"Temperature deviation exceeds the threshold by eight percent."

"The paint on the left side is cracked!" Susan exclaimed. "Hot air got in!"

Nana immediately shut off the heating in that area and switched to the backup plan.

"Switch to pulse heating to avoid local overheating."

"Can it be saved?" Chen Hao stared at the piece of metal.

"Under trial."

She manipulates the robotic arm to fine-tune the angle, with infrared monitoring providing synchronous feedback.

Thirty seconds later, the value returned to the normal range.

“The crisis is over,” she said. “The materials were not damaged.”

Everyone breathed a sigh of relief.

“Next time, apply an extra coat of paint,” Carl said.

“Or try a different brand.” Susan picked up the empty can and looked at it. “This stuff is six months past its expiration date.”

"Use it sparingly," Chen Hao said. "There might not be any supplies later."

The experiment continues.

After the final heating step, the heat preservation stage begins.

Next, we just wait.

The machine's noise level dropped.

The four people stood around the experimental setup, and no one spoke.

The near-miss they just experienced had left their hearts still pounding.

“Actually,” Karl suddenly spoke up, “I think this method can work.”

“I think so too,” Susan said.

"Don't say it's too early." Chen Hao looked at the thermal timer. "If you say it'll work now, it'll break tomorrow."

“But the idea is right,” Nana said. “Nature has spent hundreds of millions of years optimizing this structure, and we are just using it as a reference.”

"The key is that we finally have a reference point," Chen Hao smiled. "Before, we were just guessing."

“What’s next?” Carl asked.

"Trial production will officially begin tomorrow," Chen Hao said. "We'll make a complete transmission rod first and install it into the prototype machine to test it."

"Are there enough materials?"

"Use it sparingly, and that will be enough."

"What if another problem arises?"

"Then let's revise it again."

"When will it be changed?"

"Revise it until it works."

The room was quiet for a while.

“Actually,” Susan said softly, “I saw more than one kind of plant outside just now. There are a few others that grow more robustly and might be more suitable for reference.”

Chen Hao turned to look at her.

"Shall we collect some more samples tomorrow?"

She nodded.

"Nana, could you save all the data about these plants?"

“A local archive has been established,” Nana said. “It’s named the ‘Bionic Structure Reference Set’.”

“It’s a nice name,” Carl said.

“It’s better than the ‘Groundhog Project’,” Susan laughed.

"Don't delete that either." Chen Hao opened the notebook. "Keep it to commemorate our silliest moments."

He closed his notebook, walked to the control panel, and turned off the operation log.

The screen went dark.

There was no warning flashing this time.

He turned to face the three of them.

"Get some rest early tonight. Start the early shift tomorrow."

No one objected.

Carl packed up his tools. Susan removed the test piece and carefully wrapped it up. Nana disconnected the connection and started the self-test system.

Chen Hao stood at the doorway and glanced back at the piece of metal that was cooling down.

It lay quietly on the shelf, with a faint heating mark on its surface.

Like a scar.

It could also be a starting point.

He reached out and turned off the light.

The last moment before darkness falls.

Susan placed the plant samples into a sealed box.