name the venvs, so you know which one you are in.

.gitignore

@@ -10,7 +10,9 @@ syntax: glob
 __pycache__/
 *.py[co]
 .pytest_cache
-venv/
+venv_pEpACIDgen/
+venv_lib_test/
+venv_synth_shed/
 *.egg-info/
 *.egg-link
 *.egg

Makefile

@@ -1,4 +1,4 @@
-VENV_DIR = ./venv
+VENV_DIR = ./venv_pEpACIDgen
 BUILD_DIR = ./build
 DIST_DIR = ./dist
 PYTHON_ARTIFACTS += ./.eggs

examples/ext/lib_test/Makefile.conf

@@ -7,4 +7,4 @@ BUILD_INPLACE = ./lib_test/lib_test.cpython-38-darwin.so
 PYTHON_ARTIFACTS += ./.eggs
 PYTHON_ARTIFACTS += ./lib_test.egg-info
 PYTHON_ARTIFACTS += ./.pytest_cache
-VENV_DIR = ./venv
+VENV_DIR = ./venv_lib_test

examples/ext/lib_test/setup.py

@@ -9,7 +9,7 @@ ext_modules = [
         ["lib_test/lib_test.cc"],
         include_dirs=['../../lib/lib_test',
                       '/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8',
-                      'venv/lib/python3.8/site-packages/pybind11/include'],
+                      'venv_lib_test/lib/python3.8/site-packages/pybind11/include'],
         extra_compile_args=['-std=c++11'],
         libraries=['lib_test'],
         library_dirs=['../../lib/lib_test/']

examples/ext/synth_shed/Makefile.conf

@@ -7,4 +7,4 @@ BUILD_INPLACE = ./synth_shed/syth_shed.cpython-38-darwin.so
 PYTHON_ARTIFACTS += ./.eggs
 PYTHON_ARTIFACTS += ./synth_shed.egg-info
 PYTHON_ARTIFACTS += ./.pytest_cache
-VENV_DIR = ./venv
+VENV_DIR = ./venv_synth_shed

examples/ext/synth_shed/setup.py

@@ -9,7 +9,7 @@ ext_modules = [
         ["synth_shed/synth_shed.cc"],
         include_dirs=['../../lib/lib_synth_shed',
                       '/opt/local/Library/Frameworks/Python.framework/Versions/3.8/include/python3.8',
-                      'venv/lib/python3.8/site-packages/pybind11/include'],
+                      'venv_synth_shed/lib/python3.8/site-packages/pybind11/include'],
         extra_compile_args=['-std=c++11'],
         libraries=['synth_shed'],
         library_dirs=['../../lib/lib_synth_shed/']