I retrofitted a shielding gas inlet to the printhead for more testing with shielding gas. At the moment it's just a hole next to the nozzle for spraying shielding gas on the buildplate and I'm not sure whether this is enough or whether I need a proper gas nozzle. I think I will see it while testing... I will also installed a solenoid valve for starting and stopping the gas supply.
The valve can be opened in the startcode with e.g. M106 P1 S255 and closed in the endcode with M106 P1 S0. The valve I have works with 12V and so it would need a relay for operating it.