diff --git a/SConstruct b/SConstruct
index bbb2775..4f4d44c 100644
--- a/SConstruct
+++ b/SConstruct
@@ -6,59 +6,15 @@
 #
 # Eryn Wells <eryn@erynwells.me>
 
-import os
-
-import erw
+import logging
 
+setup_logging()
 
 BUILD_CMDS = get_bool_argument(ARGUMENTS.get('BUILD_CMDS', False))
 MODE = ARGUMENTS.get('MODE', None)
 
-BUILD_DIR = Dir('#build')
-LIB_DIR = Dir('#lib')
-SRC_DIR = Dir('#src')
-TEST_DIR = Dir('#test')
-
-
-modes = {
-    'debug': erw.DebugEnvironment(succinct=not BUILD_CMDS),
-    'beta': erw.BetaEnvironment(succinct=not BUILD_CMDS),
-    'release': erw.ReleaseEnvironment(succinct=not BUILD_CMDS),
-}
-
 for mode in (MODE.split(',') if MODE else ['debug']):
-    try:
-        env = modes[mode]
-    except KeyError:
-        print 'Skipping invalid mode: {}'.format(mode)
-        break
-
-    out_dir = BUILD_DIR.Dir(env['NAME'])
-
-    # Allow same directory includes.
-    env.Append(CPPPATH=['.'])
-
-    # Process all lib dirs.
-    env['AVAILABLE_LIBS'] = {}
-    for lib in os.listdir(LIB_DIR.abspath):
-        lib_dir = LIB_DIR.Dir(lib)
-        if not lib_dir.isdir():
-            print 'Skipping {} in lib directory: is not a directory'.format(lib)
-            continue
-        lib_out_dir = out_dir.Dir('lib').Dir(lib)
-        output = do_sconscript(env, LIB_DIR.Dir(lib), lib_out_dir)
-        if not output:
-            print "Lib {} didn't return any object".format(lib)
-        env['AVAILABLE_LIBS'][lib] = output
-        env.Append(LIBPATH=[lib_out_dir])
-
-    # Get source files.
-    src_out_dir = out_dir.Dir('src')
-    do_sconscript(env, SRC_DIR, src_out_dir)
-    env.Append(LIBPATH=[src_out_dir],
-               CPPPATH=[SRC_DIR])
-
-    # Get test binaries.
-    test = do_sconscript(env, TEST_DIR, out_dir.Dir('test'))
-    run_tests = env.Alias('test', [test], '{} --gtest_color=yes'.format(test[0].path))
-    env.AlwaysBuild(run_tests)
+    env = Environment.for_mode(mode)
+    env.process_lib_dirs()
+    env.process_src()
+    env.process_tests()
diff --git a/lib/gtest/SConscript b/lib/gtest/SConscript
index 07126f5..5d2e1c7 100644
--- a/lib/gtest/SConscript
+++ b/lib/gtest/SConscript
@@ -1,18 +1,8 @@
 # SConscript
 # vim: set ft=python:
-#
-# Build file for the gtest library. This file also serves as an example for how
-# to build libraries for inclusion with my SCons environment. Libraries should
-# return a build object.
-#
 # Eryn Wells <eryn@erynwells.me>
 
-import os.path
-
-Import('env')
-env.Append(CPPPATH=[Dir('include').srcnode()])
-
-files = [
+Library('gtest', [
     'gtest-all.cc',
     'gtest-death-test.cc',
     'gtest-filepath.cc',
@@ -21,7 +11,5 @@ files = [
     'gtest-test-part.cc',
     'gtest-typed-test.cc',
     'gtest.cc',
-]
-
-gtest = env.Library('gtest', files)
-Return('gtest')
+    'gtest_main.cc'
+])
diff --git a/site_scons/erw.py b/site_scons/erw.py
deleted file mode 100644
index 224e4d6..0000000
--- a/site_scons/erw.py
+++ /dev/null
@@ -1,81 +0,0 @@
-# erw.py
-# Eryn Wells <eryn@erynwells.me>
-
-import sys
-
-import SCons.Environment
-
-import paths
-
-#
-# Environments
-#
-
-class Environment(SCons.Environment.Environment):
-    '''
-    Default SCons environment for building things.
-    '''
-
-    def __init__(self, name, modern=True, paranoid=True, colorful=True, succinct=True, **kwargs):
-        super(Environment, self).__init__(**kwargs)
-
-        self['NAME'] = name
-
-        if 'CC' not in kwargs:
-            self['CC'] = self.Detect(['clang', 'gcc'])
-        if 'CXX' not in kwargs:
-            self['CXX'] = self.Detect(['clang++', 'g++'])
-        if 'LINK' not in kwargs:
-            self['LINK'] = self.Detect(['clang++', 'clang', 'ld'])
-
-        # Modern C/C++
-        if modern:
-            self.Append(CFLAGS=['-std=c99'])
-            self.Append(CXXFLAGS=['-std=c++11'])
-
-        # Paranoid C/C++
-        if paranoid:
-            self.Append(CCFLAGS=['-Wall', '-Wextra', '-pedantic'])
-
-        # Colorful C/C++
-        if colorful and sys.stdout.isatty():
-            if 'clang' in self['CC'] or 'clang' in self['CXX']:
-                self.Append(CCFLAGS=['-fcolor-diagnostics'])
-
-        self['ARCOMSTR'] = self._comstr('Archiving', succinct)
-        self['ASCOMSTR'] = self._comstr('Assembling', succinct)
-        self['ASPPCOMSTR'] = self._comstr('Assembling', succinct)
-        self['CCCOMSTR'] = self._comstr('Building (C)', succinct)
-        self['CXXCOMSTR'] = self._comstr('Building (C++)', succinct)
-        self['LINKCOMSTR'] = self._comstr('Linking', succinct)
-        self['RANLIBCOMSTR'] = self._comstr('Indexing', succinct)
-        self['SHCCCOMSTR'] = self._comstr('Building (C, Shared)', succinct)
-        self['SHCXXCOMSTR'] = self._comstr('Building (C++, Shared)', succinct)
-        self['SHLINKCOMSTR'] = self._comstr('Linking (Shared)', succinct)
-
-    def _comstr(self, action, succinct=True):
-        if succinct:
-            return '{:>25}: $TARGET'.format(action)
-        else:
-            return '  [{:^6}] $TARGET'.format(action)
-
-
-class DebugEnvironment(Environment):
-    def __init__(self, name='debug', **kwargs):
-        super(DebugEnvironment, self).__init__(name, **kwargs)
-        self.Append(CPPDEFINES=['DEBUG'])
-        self.Append(CCFLAGS=['-O0', '-g'])
-
-
-class BetaEnvironment(Environment):
-    def __init__(self, name='beta', **kwargs):
-        super(BetaEnvironment, self).__init__(name, **kwargs)
-        self.Append(CPPDEFINES=['DEBUG'])
-        self.Append(CCFLAGS=['-O3', '-g'])
-
-
-class ReleaseEnvironment(Environment):
-    def __init__(self, name='release', **kwargs):
-        super(ReleaseEnvironment, self).__init__(name, **kwargs)
-        self.Append(CPPDEFINES=['NDEBUG', 'RELEASE'])
-        self.Append(CCFLAGS=['-O3'])
diff --git a/site_scons/site_init.py b/site_scons/site_init.py
index d1412f0..e451523 100644
--- a/site_scons/site_init.py
+++ b/site_scons/site_init.py
@@ -1,6 +1,14 @@
 # site_init.py
 # Eryn Wells <eryn@erynwells.me>
 
+import logging
+import os
+import sys
+
+import SCons.Environment
+import SCons.Errors
+
+import paths
 
 def do_sconscript(env, src_dir, out_dir=None):
     '''
@@ -13,6 +21,13 @@ def do_sconscript(env, src_dir, out_dir=None):
         kwargs['variant_dir'] = out_dir
     return env.SConscript(sconscript, {'env': env}, **kwargs)
 
+
+def setup_logging(level=logging.DEBUG):
+    '''Configure global logging for the SCons system.'''
+    root = logging.getLogger()
+    root.setLevel(logging.DEBUG)
+    root.addHandler(logging.StreamHandler())
+
 #
 # Argument utils
 #
@@ -28,3 +43,204 @@ def get_bool_argument(arg):
     except ValueError:
         pass
     return str(arg).lower() != 'false'
+
+#
+# Builders
+#
+
+def program_builder(env):
+    original_builder = env.Program
+    def builder(env, prog_name, sources, *args, **kwargs):
+        return original_builder(prog_name, sources, *args, **kwargs)
+    return builder
+
+#
+# Environments
+#
+
+class Environment(SCons.Environment.Environment):
+    '''
+    Default SCons environment for building things.
+    '''
+
+    @classmethod
+    def _comstr(cls, action, succinct=True):
+        if succinct:
+            return '{:>25}: $TARGET'.format(action)
+        # Use the default *COMSTR.
+        return None
+
+    @classmethod
+    def for_mode(cls, mode, name=None, succinct=True):
+        kwargs = {'succinct': succinct}
+        if name:
+            kwargs['name'] = name
+        mode_lower = mode.lower()
+        if mode_lower == 'debug':
+            return DebugEnvironment(**kwargs)
+        elif mode_lower == 'beta':
+            return BetaEnvironment(**kwargs)
+        elif mode_lower == 'release':
+            return ReleaseEnvironment(**kwargs)
+        raise SCons.Errors.UserError('Invalid mode: {}'.format(mode))
+
+    def __init__(self, name, modern=True, paranoid=True, colorful=True, succinct=True, **kwargs):
+        super(Environment, self).__init__(**self._append_custom_tools(kwargs))
+
+        self.SetDefault(NAME=name)
+
+        self.SetDefault(LOGGER=logging.getLogger(name))
+
+        self.SetDefault(BUILD_ROOT=self.Dir('#build'))
+        self.SetDefault(LIB_ROOT=self.Dir('#lib'))
+        self.SetDefault(SRC_ROOT=self.Dir('#src'))
+        self.SetDefault(TEST_ROOT=self.Dir('#test'))
+        self.SetDefault(INCLUDE_ROOT=self.Dir('#include'))
+
+        # Allow same directory includes.
+        self.AppendUnique(CPPPATH=['.'])
+
+        self.SetDefault(CC=self.Detect(['clang', 'gcc']))
+        self.SetDefault(CXX=self.Detect(['clang++', 'g++']))
+        self.SetDefault(LINK=self.Detect(['clang++', 'clang', 'ld']))
+
+        # Modern C/C++
+        if modern:
+            self.AppendUnique(CFLAGS=['-std=c99'])
+            self.AppendUnique(CXXFLAGS=['-std=c++11'])
+
+        # Paranoid C/C++
+        if paranoid:
+            self.AppendUnique(CCFLAGS=['-Wall', '-Wextra', '-pedantic'])
+
+        # Colorful C/C++
+        if colorful and sys.stdout.isatty():
+            if 'clang' in self['CC'] or 'clang' in self['CXX']:
+                self.AppendUnique(CCFLAGS=['-fcolor-diagnostics'])
+
+        # Pretty printing
+        self.SetDefault(ARCOMSTR=Environment._comstr('Archiving', succinct))
+        self.SetDefault(ASCOMSTR=Environment._comstr('Assembling', succinct))
+        self.SetDefault(ASPPCOMSTR=Environment._comstr('Assembling', succinct))
+        self.SetDefault(CCCOMSTR=Environment._comstr('Building (C)', succinct))
+        self.SetDefault(CXXCOMSTR=Environment._comstr('Building (C++)', succinct))
+        self.SetDefault(LINKCOMSTR=Environment._comstr('Linking', succinct))
+        self.SetDefault(RANLIBCOMSTR=Environment._comstr('Indexing', succinct))
+        self.SetDefault(SHCCCOMSTR=Environment._comstr('Building (C, Shared)', succinct))
+        self.SetDefault(SHCXXCOMSTR=Environment._comstr('Building (C++, Shared)', succinct))
+        self.SetDefault(SHLINKCOMSTR=Environment._comstr('Linking (Shared)', succinct))
+
+    @property
+    def build_root(self):
+        '''Return the build output directory for this environment.'''
+        return self['BUILD_ROOT'].Dir(self['NAME'])
+
+    @property
+    def lib_root(self):
+        '''Return the root directory for libraries for this environment.'''
+        return self['LIB_ROOT']
+
+    @property
+    def src_root(self):
+        '''Return the main source root directory for this environment.'''
+        return self['SRC_ROOT']
+
+    @property
+    def lib_dirs(self):
+        for lib in os.listdir(self['LIB_ROOT'].abspath):
+            lib_dir = self['LIB_ROOT'].Dir(lib)
+            if not lib_dir.isdir():
+                continue
+            yield (lib, lib_dir)
+
+    #
+    # Library processing
+    #
+
+    def process_lib_dirs(self):
+        self.log('Processing libs in #{} ...'.format(self.lib_root.path))
+        for name, lib in self.lib_dirs:
+            self.log('  - {}'.format(name))
+            self.LibDir(name)
+
+    def process_src(self):
+        out_dir = self.build_root.Dir('src')
+        # TODO: Do the thing.
+        # do_sconscript(env, env.source_root, src_out_dir)
+        self.Append(CPPPATH=[self.src_root])
+
+    def lib(self, name):
+        return self['LIBS'].get(name)
+
+    def register_lib(self, name, lib):
+        if name in self['LIBS']:
+            self.log_error('Library has already been built: {}'.format(name))
+        self['LIBS'][name] = lib
+
+    #
+    # Test processing
+    #
+
+    def test_objects(self, name):
+        self._ensure_test_structure(name)
+        return self['TESTS'][name]['objects']
+
+    def test_program(self, name):
+        self._ensure_test_structure(name)
+        return self['TESTS'][name]['program']
+
+    def register_test_program(self, name, prog):
+        self._ensure_test_structure(name)
+        self['TESTS'][name]['program'] = prog
+
+    def process_tests(self):
+        for test, struct in self['TESTS'].iteritems():
+            if not struct['program']:
+                continue
+            self.TestRun(test)
+
+    def _ensure_test_structure(self, name):
+        self['TESTS'].setdefault(name, {'program': None, 'objects': []})
+
+    #
+    # Logging
+    #
+
+    def log(self, msg, *args, **kwargs):
+        self['LOGGER'].info(msg, *args, **kwargs)
+
+    def log_debug(self, msg, *args, **kwargs):
+        self['LOGGER'].debug(msg, *args, **kwargs)
+
+    def log_error(self, msg, *args, **kwargs):
+        self['LOGGER'].error(msg, *args, **kwargs)
+
+    def _append_custom_tools(self, kwargs):
+        '''Add custom tools to the `kwargs`.'''
+        tools = kwargs.setdefault('tools', ['default'])
+        for tool in ['lib', 'test']:
+            if tool in tools:
+                continue
+            tools.append(tool)
+        return kwargs
+
+
+class DebugEnvironment(Environment):
+    def __init__(self, name='debug', **kwargs):
+        super(DebugEnvironment, self).__init__(name, **kwargs)
+        self.Append(CPPDEFINES=['DEBUG'])
+        self.Append(CCFLAGS=['-O0', '-g'])
+
+
+class BetaEnvironment(Environment):
+    def __init__(self, name='beta', **kwargs):
+        super(BetaEnvironment, self).__init__(name, **kwargs)
+        self.Append(CPPDEFINES=['DEBUG'])
+        self.Append(CCFLAGS=['-O3', '-g'])
+
+
+class ReleaseEnvironment(Environment):
+    def __init__(self, name='release', **kwargs):
+        super(ReleaseEnvironment, self).__init__(name, **kwargs)
+        self.Append(CPPDEFINES=['NDEBUG', 'RELEASE'])
+        self.Append(CCFLAGS=['-O3'])
diff --git a/site_scons/site_tools/lib.py b/site_scons/site_tools/lib.py
new file mode 100644
index 0000000..212bd6b
--- /dev/null
+++ b/site_scons/site_tools/lib.py
@@ -0,0 +1,59 @@
+# lib.py
+# Eryn Wells <eryn@erynwells.me>
+
+'''
+SCons builder for a lib directory.
+'''
+
+import SCons.Errors
+import SCons.Script
+
+
+def _process_lib_dir(env, lib, src_dir=None, out_dir=None, inc_dir=None):
+    if not src_dir:
+        src_dir = env.lib_root.Dir(lib)
+    if not src_dir.isdir():
+        err = 'Invalid library source directory: {}'.format(src_dir)
+        env.log_error(err)
+        raise SCons.Errors.UserError(err)
+    if not out_dir:
+        out_dir = env.build_root.Dir('lib').Dir(lib)
+    if not inc_dir:
+        include_dir = src_dir.Dir('include')
+        if include_dir.isdir():
+            inc_dir = [include_dir]
+    env.Append(CPPPATH=inc_dir)
+    exports = {'Library': env.Library,
+               'StaticLibrary': env.StaticLibrary,
+               'SharedLibrary': env.SharedLibrary}
+    SCons.Script._SConscript.GlobalDict.update(exports)
+    out = env.SConscript(src_dir.File('SConscript'),
+                         {'env': env.Clone()},
+                         variant_dir=out_dir,
+                         exports=exports)
+    return out
+
+
+def _build_library(env, lib_func):
+    original_builder = lib_func
+
+    def builder(env, lib_name, sources, *args, **kwargs):
+        lib = original_builder(lib_name, sources, *args, **kwargs)
+        env.register_lib(lib_name, lib)
+        return lib
+
+    return builder
+
+#
+# SCons tool interface
+#
+
+def generate(env):
+    env.SetDefault(LIBS={})
+    env.AddMethod(_process_lib_dir, 'LibDir')
+    env.AddMethod(_build_library(env, env.Library), 'Library')
+    env.AddMethod(_build_library(env, env.StaticLibrary), 'StaticLibrary')
+    env.AddMethod(_build_library(env, env.SharedLibrary), 'SharedLibrary')
+
+def exists(env):
+    return True
diff --git a/site_scons/site_tools/test.py b/site_scons/site_tools/test.py
new file mode 100644
index 0000000..df8e924
--- /dev/null
+++ b/site_scons/site_tools/test.py
@@ -0,0 +1,51 @@
+# test.py
+# Eryn Wells <eryn@erynwells.me>
+
+'''
+Test builder for SCons. Test files are compiled to objects and stored in the 
+environment.
+'''
+
+def _process_test_dir(env, dir, program=None):
+    # TODO: Builder for test directories?
+    pass
+
+
+def _build_test_object(env, source, program=None):
+    obj = env.Object(source)
+    if not program:
+        program = 'test'
+    try:
+        env.test_objects(program).extend(obj)
+    except TypeError:
+        env.test_objects(program).append(obj)
+    return obj
+
+
+def _build_test_program(env, name=None):
+    if not name:
+        name = 'test'
+    prog = env.Program(name, env.test_objects(name), LIBS=[env.lib('gtest')])
+    env.register_test_program(name, prog)
+    return 
+
+
+def _run_tests(env, name=None):
+    if not name:
+        name = 'test'
+    cmd = env.Command(env.test_program(name), None, '$SOURCE --gtest_color=yes')
+    env.AlwaysBuild(cmd)
+    return cmd
+
+#
+# SCons tool interface
+#
+
+def generate(env):
+    env.SetDefault(TESTS={})
+    env.AddMethod(_build_test_object, 'Test')
+    env.AddMethod(_build_test_program, 'TestProgram')
+    env.AddMethod(_run_tests, 'TestRun')
+
+def exists(env):
+    return 'Object' in env