Make sure both hnsd and fingertip binaries are in ./appdir/usr/bin/.
Download / install linuxdeploy.
Then build AppImage.
# download linuxdeploy
wget -c -nv "https://github.com/linuxdeploy/linuxdeploy/releases/download/continuous/linuxdeploy-x86_64.AppImage"
chmod +x linuxdeploy-x86_64.AppImage
# build
./linuxdeploy-x86_64.AppImage --appdir appdir --output appimageAppImage will be in current directory.