5. Imagepacker

Create a new folder named packer:
mkdir packer

enter the folder packer:
cd packer

download the packer script:
wget https://raw.githubusercontent.com/petit-miner/Blueberry-PI/master/Software/Image-packer/pack_img.sh

create two folders:
mkdir boot && mkdir rootfs
Now you need to copy the kernel (zImage),
the devicetree (sun8i-v3s-blueberrypi-xx.dtb),
the U-boot bin file (u-boot-sunxi-with-spl.bin)
and the boot.scr file into the boot/ folder.
After that copy the rootfs.tar into the rootfs folder.
Now untar the archive:
sudo tar xvf rootfs.tar

Now you need to run the packer script:
sudo ./pack_zero_img.sh boot/ rootfs/

Now you are done, the packer script created a bootable image which you can now flash to a SD-card.