initial, untested

Makefile

@@ -0,0 +1,38 @@
+# You need to run the following to let make work:
+#    sudo xcodebuild -license accept
+
+# install the following to /Applications before proceeding:
+#     * CreateUserPkg
+#     * AutoDMG.app
+#     * the OSX installer (Install macOS Sierra.app)
+#     * Xcode.app
+# to /Applications before proceeding.
+
+OSX := /Applications/Install macOS Sierra.app
+AUTODMG := /Applications/AutoDMG.app/Contents/MacOS/AutoDMG
+OUTPUT := $(shell date +%Y%m%d).osx.10.12.adminadmin.dmg
+
+default: $(OUTPUT)
+
+prepare:
+	sudo pmset -a sleep 180
+	sudo pmset -a displaysleep 180
+	$(AUTODMG) update
+
+$(OUTPUT): prepare custompkg/custom.pkg
+	-$(AUTODMG) \
+		--log-level 7 \
+		--logfile - \
+		build \
+		-n "root" \
+		-u -U \ -o /tmp/output.dmg \
+		"$(OSX)" \
+		/Applications/Xcode.app \
+		/Applications/AutoDMG.app \
+		/Applications/CreateUserPkg.app \
+		"$(OSX)" \
+		$(PWD)/pkgs/*.pkg \
+		cp /tmp/output.dmg $(PWD)/$@
+
+clean:
+	rm custompkg/custom.pkg