How to generate board outline

I was looking into the seeedstudio submission requirement and they ask for board outline file "pcbname.GML/GKO "

Any suggestion?

Just rename the generated gerber file for edge.cuts layer to .gko, that’s all.

Yeah, I always feel uncomfortable doing that kind of thing but it’s just convention and which programs use which extensions. The gerber info is nearly always the same.

Different fabs often ask for differently named drill files too. *.drl and *.txt are fairly common extentions.