I could finally do it. One part 3d printed gear box. I offered 3BFAB to use it as their demo part. It would probably be @3bfabrika ‘s demo part which they would give it to their potential consumers. It was printed as same as how you see it in the photo, and it is a gear box that it isn’t able to be disassembled, and it isn’t an assembled gear box too! As information, I AM ONLY 14 years old. I designed it with @SolidWorks (Also I passed CSWA exam (220 out of 240)). I printed it with @MakerBot.