Here is the original post.
To do this copy and paste these into terminal to make the bootable iso file (assuming you have already downloaded Sierra to your Applications folder via the mac app store):
hdiutil attach /Applications/Install\ macOS\ Sierra.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app
hdiutil create -o /tmp/Sierra.cdr -size 7500m -layout SPUD -fs HFS+J
hdiutil attach /tmp/Sierra.cdr.dmg -noverify -nobrowse -mountpoint /Volumes/install_build
asr restore -source /Volumes/install_app/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase
rm /Volumes/OS\ X\ Base\ System/System/Installation/Packages
cp -rp /Volumes/install_app/Packages /Volumes/OS\ X\ Base\ System/System/Installation/
cp -rp /Volumes/install_app/BaseSystem.chunklist /Volumes/OS\ X\ Base\ System/BaseSystem.chunklist
cp -rp /Volumes/install_app/BaseSystem.dmg /Volumes/OS\ X\ Base\ System/BaseSystem.dmg
hdiutil detach /Volumes/install_app
hdiutil detach /Volumes/OS\ X\ Base\ System/
hdiutil convert /tmp/Sierra.cdr.dmg -format UDTO -o /tmp/Sierra.iso
mv /tmp/Sierra.iso.cdr ~/Desktop/Sierra.iso
A bootable iso file called Sierra.iso will then appear on your desktop and you can use this to burn it to a dual layer dvd:
sudo drutil burn /Users/YOURNAME/Desktop/Sierra.iso
where you replace "YOURNAME" with the username for the account you are logged into at the time.
and then boot to startup manager with option key to select the dvd.
