add build files to produce the gcode

Makefile

@@ -1,11 +1,27 @@
 PREFIX=/usr
 SHAREDIR=$(PREFIX)/share/models
+PRINT_TEMP=220
+PRINT_BED_TEMP=65
+PRINT_NOZZLE_DIAM=0.4
+PRINT_FILA_DIAM=1.75
+# XXX: Slic2r doesn't always set the bed temperature correctly. fix by specifying it also for the first layer.
+SLIC3R_FLAGS=\
+	--temperature $(PRINT_TEMP) \
+	--first-layer-temperature $(PRINT_TEMP) \
+	--bed-temperature $(PRINT_BED_TEMP) \
+	--first-layer-bed-temperature $(PRINT_BED_TEMP) \
+	--nozzle-diameter $(PRINT_NOZZLE_DIAM) \
+	--filament-diameter $(PRINT_FILA_DIAM)
 
-all: case.stl
+all: build/case.stl build/case.gcode
 
-%.stl: %.scad
+build/%.stl: %.scad
+	mkdir -p build
 	openscad $^ -o $@
 
+%.gcode: %.stl
+	slic3r $(SLIC3R_FLAGS) %^ -o $@
+
 install:
 	mkdir -p $(SHAREDIR)
 	install -m644 case.stl $(SHAREDIR)