diff --git a/PyTeX/build/build/builder.py b/PyTeX/build/build/builder.py
index be88582..b45dcf5 100644
--- a/PyTeX/build/build/builder.py
+++ b/PyTeX/build/build/builder.py
@@ -1,9 +1,13 @@
 from pathlib import Path
-from typing import Optional, Union
+from typing import Optional, Union, List
 
 from .enums import PyTeXRootDirType
 from .pytex_config import PyTeXConfig
 from ...logger import logger
+from .constants import *
+from ..versioning.version_info.version_info import FileVersionInfo
+from .pytex_file import PyTeXSourceFile
+from .relative_path import RelativePath
 
 
 class PyTeXBuilder:
@@ -22,23 +26,35 @@ class PyTeXBuilder:
             self._pytex_config: Optional[PyTeXConfig] = pytex_config
             self._root_dir: Optional[Path] = root_dir
 
+        # Non-public attributes
+        self._version_info: Optional[FileVersionInfo] = None
+        self._pytex_files: Optional[List[PyTeXSourceFile]] = None
+
     def build_tex_sources(self):
         self._build_target_type = PyTeXRootDirType.TEX_SOURCE
-        pass
+        self._build()
 
     def build_documentation(self):
         self._build_target_type = PyTeXRootDirType.DOC
-        pass
+        self._build()
 
     def build_tex_files(self):
         self._build_target_type = PyTeXRootDirType.BUILD
-        pass
+        self._build()
 
     def build(self):
         if self._build_target_type is None:
             raise NotImplementedError
         self._build()
 
+    @property
+    def version_info(self):
+        if self._version_info is None:
+            self._version_info = FileVersionInfo.from_json(
+                self.target_root / VERSION_INFO_FILE
+            )
+        return self._version_info
+
     @property
     def pytex_config(self) -> PyTeXConfig:
         if self._pytex_config is None:
@@ -68,5 +84,46 @@ class PyTeXBuilder:
     def parse_config_file(self):
         pass
 
+    @classmethod
+    def supported_extensions(cls) -> List[str]:
+        return [
+            '.sty.pytex',
+            '.cls.pytex',
+            '.dtx.pytex',
+            '.dict.pytex',
+            '.tex.pytex',
+            '.sty',
+            '.cls',
+            '.dtx',
+            '.dict',
+            '.tex',
+        ]
+
+    def is_supported_file(self, filename: str) -> bool:
+        return True in [
+            filename.endswith(extension)
+            for extension in self.supported_extensions()
+        ]
+
+    def load_pytex_files(self):
+        self._pytex_files = []
+        if self.pytex_config.recursive:
+            files = self.source_root.rglob('*')
+        else:
+            files = self.source_root.glob('*')
+        for file in files:
+            if self.is_supported_file(file.name):
+                self._pytex_files.append(
+                    PyTeXSourceFile(
+                        relative_path=RelativePath(
+                            file,
+                            root_dir=self.source_root
+                        )
+                    )
+                )
+
     def _build(self):
         logger.info("Starting build")
+        self.load_pytex_files()
+        raise NotImplementedError
+
diff --git a/PyTeX/build/build/constants.py b/PyTeX/build/build/constants.py
index 0b8f0f7..6a50168 100644
--- a/PyTeX/build/build/constants.py
+++ b/PyTeX/build/build/constants.py
@@ -12,3 +12,5 @@ YAML_BUILD = 'build'
 YAML_DEFAULT = 'default'
 YAML_CONFIGS = 'configs'
 YAML_DIRS = 'dirs'
+
+VERSION_INFO_FILE = 'version_info.json'
diff --git a/PyTeX/build/build/pytex_file.py b/PyTeX/build/build/pytex_file.py
index 39a5241..9529b34 100644
--- a/PyTeX/build/build/pytex_file.py
+++ b/PyTeX/build/build/pytex_file.py
@@ -38,7 +38,7 @@ class PyTeXSourceFile:
 
     @property
     def output_files(self) -> List[RelativePath]:
-        files = self._formatter.output_files
+        files = self.formatter.output_files
         files = [
             self._relative_path.with_name(filename)
             for filename in files
diff --git a/main.py b/main.py
index c3c5c59..9779118 100644
--- a/main.py
+++ b/main.py
@@ -51,4 +51,6 @@ pytex_config = PyTeXConfig.from_yaml(conf_path)
 
 builder = PyTeXBuilder(conf_path)
 
+builder.build_tex_sources()
+
 pass