Install custom rom via default recovery

Graphicscore

Hi, is it possible to install a self build android version for the rk3399 via the default recovery that is already installed on the board ? (eg. creating a flashable zip that can flash in stock rom). Or is it only possible to flash it with rktools / upgrade_tool ?
Best regards,

isle

Yes it is possible.
But we do not suggest you to do this unless you are very familiar with this.