there's a typo from step "Create the CD image directory and populate it" 2 - 4, and fix issue (atleast for me, i hope others not experiencing it)

[ChristoferRian]

the folder "image" in the description missing "/" at the front name, it should be :

2. Copy Kernel Images
   cp /boot/vmlinuz-**-**-generic /image/casper/vmlinuz
cp /boot/initrd.img-**-**-generic /image/casper/initrd

3. Copy memtest86+ binary (BIOS)
   cp /boot/memtest86+.bin /image/install/memtest86+

4. Download and extract memtest86 binary (UEFI)
   wget --progress=dot https://www.memtest86.com/downloads/memtest86-usb.zip -O /image/install/memtest86-usb.zip
   [solve the issue]
   sudo chmod 755 /image/install/
unzip -p /image/install/memtest86-usb.zip memtest86-usb.img > /image/install/memtest86
rm -f /image/install/memtest86-usb.zip

---

the issue i'm experiencing is permission denied when unzip memtest86-usb.zip

[ChristoferRian]

NO PLEASE I WAS WRONG
I'M REALLY SORRY, you were right the first one

Copy Kernel Images
cp boot/vmlinuz-**-**-generic image/casper/vmlinuz
cp boot/initrd.img-**-**-generic image/casper/initrd

Copy memtest86+ binary (BIOS)
cp boot/memtest86+.bin image/install/memtest86+

Download and extract memtest86 binary (UEFI)
wget --progress=dot https://www.memtest86.com/downloads/memtest86-usb.zip -O image/install/memtest86-usb.zip
[solve the issue]
sudo chmod 755 image/install/
unzip -p image/install/memtest86-usb.zip memtest86-usb.img > image/install/memtest86
rm -f image/install/memtest86-usb.zip