diff --git a/Makefile b/Makefile
index 5d0fa02..6d7dde9 100644
--- a/Makefile
+++ b/Makefile
@@ -67,12 +67,12 @@ install:
 	install -m644 build/case.stl $(SHAREDIR)
 	install -m644 build/case.gcode $(SHAREDIR)
 
-%/pinephone_case.vtk %/pinephone_case.vtk.js: cq_toplevel.py src/*.py
+%/pinephone_case.vtk %/pinephone_case.vtk.js: main.py src/*.py
 	mkdir -p "$(@D)"
-	./cq_toplevel.py --export-vtk $*/pinephone_case.vtk
-%/pinephone_phone.vtk %/pinephone_phone.vtk.js: cq_toplevel.py src/*.py
+	./main.py --export-vtk $*/pinephone_case.vtk
+%/pinephone_phone.vtk %/pinephone_phone.vtk.js: main.py src/*.py
 	mkdir -p "$(@D)"
-	./cq_toplevel.py --render-phone-only --export-vtk $*/pinephone_phone.vtk
+	./main.py --render-phone-only --export-vtk $*/pinephone_phone.vtk
 
 build/web-viewer/vtk.js: doc.in/vtk.js
 	mkdir -p build/web-viewer
@@ -84,12 +84,12 @@ build/web-viewer/index.html: doc.in/index.html build/web-viewer/vtk.js build/web
 	mkdir -p build/web-viewer
 	cp $< $@
 
-%_case.png: cq_toplevel.py src/*.py
+%_case.png: main.py src/*.py
 	mkdir -p "$(@D)"
-	./cq_toplevel.py --export-png $@
-%_case_with_phone.png: cq_toplevel.py src/*.py
+	./main.py --export-png $@
+%_case_with_phone.png: main.py src/*.py
 	mkdir -p "$(@D)"
-	./cq_toplevel.py --render-phone --export-png $@
+	./main.py --render-phone --export-png $@
 
 readme: readme_files/pinephone_front_case_with_phone.png readme_files/pinephone_back_case_with_phone.png readme_files/pinephone_side_case_with_phone.png
 
@@ -98,9 +98,9 @@ doc: readme build/web-viewer/index.html
 clean:
 	rm -rf build
 
-build/case.stl: cq_toplevel.py src/*.py
+build/case.stl: main.py src/*.py
 	mkdir -p "$(@D)"
-	./cq_toplevel.py --export-stl $@
+	./main.py --export-stl $@
 
 %.gcode: %.stl
 	mkdir -p $(shell dirname $@)
diff --git a/README.md b/README.md
index 11718a5..5b5b35c 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@ this is a 3d-printable case designed for the PinePhone,
 but implemented with an eye towards generalizing beyond just that model
 and supporting future phones/preferences alongside this first model.
 
-as an example, the default case (pictured below) includes a pouch for carrying an external battery, but if you don't want the pouch then you can build with `CASE_BATTERY=none make` (or edit with `CASE_BATTERY=none cq-toplevel.py --editor`, etc).
+as an example, the default case (pictured below) includes a pouch for carrying an external battery, but if you don't want the pouch then you can build with `CASE_BATTERY=none make` (or edit with `CASE_BATTERY=none main.py --editor`, etc).
 
 the battery pouch is the defining feature of this case though. it's a quick solution to achieve all-day battery life without any special requirements from the OS, and it requires no supports to print: it's a simple mesh which prints flat with the rest of the case, but deforms to fit the battery upon installation.
 
@@ -30,10 +30,10 @@ you'll need a browser which supports webGL (e.g. chromium).
 
 ## Building
 
-- `./cq_toplevel.py --export-stl model.stl`
+- `./main.py --export-stl model.stl`
 
 ## Development
-- `./cq_toplevel.py --editor` or `cq-editor ./cq_toplevel.py` to load an interactive GUI
+- `./main.py --editor` or `cq-editor ./main.py` to load an interactive GUI
   - press the green play button to render the model
   - call with `--render-phone` to see how the phone would fit inside the case
 
diff --git a/cq_toplevel.py b/main.py
similarity index 87%
rename from cq_toplevel.py
rename to main.py
index a671707..ec67554 100755
--- a/cq_toplevel.py
+++ b/main.py
@@ -1,10 +1,18 @@
 #!/usr/bin/env python3
 """
-toplevel file used for interactive modeling.
+toplevel file used for interactive modeling and also data exports.
 
-- `cq-editor ./cq_toplevel.py`
-- then press green play button to render
-- edit files externally, and press render again to refresh the view
+use like:
+- `main.py --editor` => to edit the case interactively
+  - then press green play button to render
+  - edit files externally, and press render again to refresh the view
+  - this is shorthand for `cq-editor ./main.py`
+- `main.py --export-stl build/case.stl` => to export the case as stl
+
+every operation works over a parameterized model. you can control this parameterization with environment variables (or flags -- see extended --help):
+- CASE_RENDER_PHONE=1  => render not just the case, but also what it would look like with the phone inside
+- CASE_RENDER_PHONE_ONLY=1  => render ONLY the phone, no case
+- CASE_BATTERY=<name>  => design the case to fit a specific battery model, or "none".
 """
 
 import cadquery as cq