After the Milano crashed, we saw Rocket repairing the damage using some tool that appears to be a cross between a 3D printer and a paint sprayer:
This resembles nothing else we've seen in the MCU thus far, and unfortunately the film goes into absolutely no detail as to what exactly that tool is or where it came from. The script is even less helpful, saying only this:
Rocket is SOLDERING the ship.
What he's doing sure looks more advanced than soldering to me…
So is this tool something Rocket built, or did he acquire it somehow?