[OnePlus 3 Guides, News, & Discussion] DavidXanatos:
I documented my build endeavor step by step in a clean VM, using a lot of snapshots to always troubleshoot from a clean strait forward state, here is the result.

Anyone who wants to build CM13 for the OnePlus 3 just has to blindly execute the below list of commands, thinking is here totally optional :p

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# Building CM 13 for OnePlus 3 using a clean Ubuntu 16.04 VM

#

# make a VM snapshot “Clean”

# install eclipse for the android SDK

sudo apt-get install eclipse

sudo apt-get install lib32z1 lib32ncurses5 libbz2-1.0:i386 lib32stdc++6

# install android SDK

# download it and unpack to ~/

cd ~/android-studio/bin/

sh ./studio.sh

# than use the configure option to install all ARM packages for your target android version, use 6.0 for cm13

# install other build tools

sudo apt-get install bison build-essential curl flex git gnupg gperf libesd0-dev liblz4-tool libncurses5-dev libsdl1.2-dev libwxgtk3.0-dev libxml2 libxml2-utils lzop maven pngcrush schedtool squashfs-tools xsltproc zip zlib1g-dev

sudo apt-get install g++-multilib gcc-multilib lib32ncurses5-dev lib32readline6-dev lib32z1-dev

sudo apt-get install maven

# make a VM snapshot “Tools”

# install the right java version for the cm version you want to build for 13 its 1.7

sudo apt-get purge openjdk-\* icedtea-\* icedtea6-\*

sudo add-apt-repository ppa:openjdk-r/ppa

sudo apt-get update

sudo apt-get install openjdk-7-jdk

# install and sync repo

git config --global user.email "me@example.com"

git config --global user.name "me"

mkdir -p ~/bin

mkdir -p ~/android/system

curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo

chmod a+x ~/bin/repo

# logout and back in to update the path variables

cd ~/android/system/

repo init -u https://github.com/CyanogenMod/android.git -b cm-13.0

# manually update the roomservice.xml

# ~/android/system/.repo/local_manifests/roomservice.xml

<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<project name="CyanogenMod/android_device_oppo_common" path="device/oppo/common" remote="github" />
<project name="CyanogenMod/android_device_qcom_common" path="device/qcom/common" remote="github" />

<project name="TheMuppets/proprietary_vendor_oneplus" path="vendor/oneplus" remote="github" revision="cm-13.0" />
<project name="CyanogenMod/android_device_oneplus_oneplus3" path="device/oneplus/oneplus3" remote="github" revision="cm-13.0" />
<project name="CyanogenMod/android_kernel_oneplus_msm8996" path="kernel/oneplus/msm8996" remote="github" revision="cm-13.0" />

<project name="CyanogenMod/android_vendor_nxp-nfc_opensource_Nfc" path="vendor/nxp-nfc/opensource/Nfc" remote="github" revision="cm-13.0" />
<project name="CyanogenMod/android_vendor_nxp-nfc_opensource_frameworks" path="vendor/nxp-nfc/opensource/frameworks" remote="github" revision="cm-13.0" />
<project name="CyanogenMod/android_vendor_nxp-nfc_opensource_libnfc-nci" path="vendor/nxp-nfc/opensource/libnfc-nci" remote="github" revision="cm-13.0" />
</manifest>

repo sync

# make another VM snapshot “Repo”

# now we proceed to build the source

cd ~/android/system/

source build/envsetup.sh

breakfast oneplus3

# add “export USE_CCACHE=1” to ~/.bashrc

# log out and back in to reload ~/.bashrc

cd ~/android/system/

source build/envsetup.sh

prebuilts/misc/linux-x86/ccache/ccache -M 50G

make clobber

brunch oneplus3

# make another VM snapshot “Build”

### done :D