Just put a ROM.zip into executable file directory.
Then select zip and press option 1 for unpack android images, after make some modifications to system folder/files,
then repack into its original android format using option 2.

Unpack vendor.img/.dat.br, system.img/.dat.br, payload.bin automatically.
Repack vendor.img/.dat.br, system.img/.dat.br,  exception for payload.bin but this tool deliver to you system.img ext4 for flashing purposes.
URTool deliver to you original system permissions and symlinks

See credits.txt for binary authors

--> Redmi Note 3 Pro (kenzo), tested on stock Miui 10 with android 6.0.1, it booted up satisfactorily.
    tested using official Lineage OS 14.1 under android 7.1 and it booted up satisfactorily.
    tested using android 8.1 and it works too.
*Not working on android 9 roms yet, make_ext4fs binary is not present in Pie repository*