You can — it is plain text — but tread carefully. Safe edits: tweaking the feedrate (F), adjusting the pre-heat dwell, or fixing axis letters to match your firmware. Risky edits: do not turn approach/return moves into G0 rapids (the wire must never race uncontrolled), do not remove the wire-on/pre-heat sequence (you will cut cold), and do not reorder moves without understanding the wire path, or you may rake the wire through finished foam.
Better still, change these in cncfoam.com and re-export, so the whole file stays consistent and the safety logic (G1-only, pre-heat, wire on/off) is preserved. Hand-editing is for small fixes, not for restructuring the cut.
Better still, change these in cncfoam.com and re-export, so the whole file stays consistent and the safety logic (G1-only, pre-heat, wire on/off) is preserved. Hand-editing is for small fixes, not for restructuring the cut.