diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6b90c35
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+**/__pycache__/
+venv
+
+tests/core/pyspec/builderspec/bellatrix.py
+tests/core/pyspec/builderspec/capella.py
diff --git a/.gitmodules b/.gitmodules
index 81aceec..eb543ab 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "beacon-apis"]
 	path = beacon-apis
 	url = git@github.com:ethereum/beacon-APIs.git
+[submodule "consensus-specs"]
+	path = consensus-specs
+	url = https://github.com/ethereum/consensus-specs
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..b618f4e
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,27 @@
+SPEC_DIR = ./specs
+TESTS_DIR = ./tests/core
+
+PY_SPEC_DIR = $(TESTS_DIR)/pyspec
+SPEC_MODULE_DIR = $(PY_SPEC_DIR)/builderspec
+
+SPECS = bellatrix capella
+
+clean:
+	rm -rf venv;
+	@for spec in $(SPECS) ; do \
+		rm -rf $(SPEC_MODULE_DIR)/$$spec; \
+	done
+
+# make (i.e. generate) the pyspec
+pyspec:
+	python3 -m venv venv
+	. venv/bin/activate
+	pip install marko
+	pip install git+https://github.com/ethereum/consensus-specs.git
+	python3 spec.py --specs $(SPECS)
+
+# test the pyspec
+test: pyspec
+	. venv/bin/activate
+	pip install pytest
+	python3 -m pytest $(PY_SPEC_DIR)/builderspec/test
diff --git a/consensus-specs b/consensus-specs
new file mode 160000
index 0000000..1c424d7
--- /dev/null
+++ b/consensus-specs
@@ -0,0 +1 @@
+Subproject commit 1c424d76eddbacae3cbffed8276264b46951456b
diff --git a/spec.py b/spec.py
new file mode 100644
index 0000000..d463dd3
--- /dev/null
+++ b/spec.py
@@ -0,0 +1,217 @@
+from enum import IntEnum
+from typing import Dict, NamedTuple, List, Sequence, Optional, TypeVar, Tuple
+
+import ast
+import os
+import string
+
+from marko.block import Heading, FencedCode, LinkRefDef, BlankLine
+from marko.inline import CodeSpan
+from marko.ext.gfm import gfm
+from marko.ext.gfm.elements import Table
+from pathlib import Path
+
+def is_variable_constant(name: str) -> bool:
+    if name[0] not in string.ascii_uppercase + '_':
+        return False
+    return all(map(lambda c: c in string.ascii_uppercase + '_' + string.digits, name[1:]))
+
+class VariableDefinition(NamedTuple):
+    type_name: Optional[str]
+    value: str
+
+def parse_variable_def(name: str, typed_value: str) -> VariableDefinition:
+    typed_value = typed_value.strip()
+    if '(' not in typed_value:
+        return VariableDefinition(type_name=None, value=typed_value)
+
+    i = typed_value.index('(')
+    type_name = typed_value[:i]
+    return VariableDefinition(type_name=type_name, value=typed_value)
+
+class SpecObject(NamedTuple):
+    functions: Dict[str, str]
+    custom_types: Dict[str, str]
+    constant_vars: Dict[str, VariableDefinition]
+    ssz_objects: Dict[str, str]
+
+def get_source_from_code_block(code: FencedCode) -> str:
+    return code.children[0].children.strip()
+
+def get_function_name_from_source(source: str) -> str:
+    fn = ast.parse(source).body[0]
+    return fn.name
+
+def get_class_info_from_source(source: str) -> Tuple[str, Optional[str]]:
+    class_def = ast.parse(source).body[0]
+    base = class_def.bases[0]
+    if isinstance(base, ast.Name):
+        parent_class = base.id
+    else:
+        parent_class = None
+    return class_def.name, parent_class
+
+class TableCols(IntEnum):
+    NAME = 0
+    VALUE = 1
+
+def get_spec(file_name: Path) -> SpecObject:
+    functions: Dict[str, str] = {}
+    constant_vars: Dict[str, VariableDefinition] = {}
+    ssz_objects: Dict[str, str] = {}
+    custom_types: Dict[str, str] = {}
+
+    with open(file_name) as source_file:
+        document = gfm.parse(source_file.read())
+
+    for child in document.children:
+        if isinstance(child, FencedCode):
+            if child.lang != "python":
+                continue
+            source = get_source_from_code_block(child)
+            if source.startswith("def"):
+                function_name = get_function_name_from_source(source)
+                function_def = "\n".join(line.rstrip() for line in source.splitlines())
+                functions[function_name] = function_def
+            elif source.startswith("class"):
+                class_name, parent_class_name = get_class_info_from_source(source)
+                if parent_class_name:
+                    assert parent_class_name == "Container"
+                ssz_objects[class_name] = "\n".join(line.rstrip() for line in source.splitlines())
+        elif isinstance(child, Table):
+            for row in child.children:
+                cells = row.children
+                assert len(cells) >= 2
+
+                name = cells[TableCols.NAME].children[0].children
+                value = cells[TableCols.VALUE].children[0].children
+
+                if isinstance(value, list):
+                    # marko parses `**X**` as a list `[X]`
+                    value = value[0].children
+
+                if not is_variable_constant(name):
+                    # Check whether the (name, value) defines a custom type (i.e. type alias)
+                    if value.startswith(("uint", "Bytes", "ByteList", "Union", "Vector", "List", "ByteVector")):
+                        custom_types[name] = value
+                    continue
+                
+                var_def = parse_variable_def(name, value)
+                constant_vars[name] = var_def
+        else:
+            continue
+
+    return SpecObject(
+        functions=functions,
+        custom_types=custom_types,
+        constant_vars=constant_vars,
+        ssz_objects=ssz_objects,
+    )
+
+def object_to_spec(spec: SpecObject) -> str:
+    constant_vars = [f"{name} = {var.value}" if var.type_name is None else f"{name}: {var.type_name} = {var.value}" for (name, var) in spec.constant_vars.items()]
+    spec = (
+            "\n\n".join(spec.custom_types.values())
+            + ("\n\n" if len(spec.custom_types) > 0 else "")
+            + "\n".join(constant_vars)
+            + ("\n\n" if len(spec.constant_vars) > 0 else "")
+            + "\n\n".join(spec.ssz_objects.values())
+            + ("\n\n" if len(spec.ssz_objects) > 0 else "")
+            + "\n\n".join(spec.functions.values())
+    )
+    return spec
+
+def combine_specs(x: SpecObject, y: SpecObject) -> SpecObject:
+    functions = {**x.functions, **y.functions}
+    custom_types = {**x.custom_types, **y.custom_types}
+    constant_vars = {**x.constant_vars, **y.constant_vars}
+    ssz_objects = {**x.ssz_objects, **y.ssz_objects}
+
+    return SpecObject(
+        functions=functions,
+        custom_types=custom_types,
+        constant_vars=constant_vars,
+        ssz_objects=ssz_objects,
+    )
+
+def build_spec(files: Sequence[Path]) -> SpecObject:
+    assert len(files) > 0
+    specs = [get_spec(spec) for spec in files]
+
+    assert len(specs) > 0
+    total_spec = specs[0]
+    for spec in specs[1:]:
+        total_spec = combine_specs(total_spec, spec)
+
+    return total_spec 
+
+def spec_files(spec: str) -> Sequence[Path]:
+    root = os.path.dirname(__file__)
+    root = os.path.join(root, "specs", spec)
+
+    spec_files = []
+    for root, dirs, files in os.walk(root):
+        for file in files:
+            if file.endswith(".md"):
+                spec_files.append(os.path.join(root, file))
+    return spec_files
+
+BELLATRIX_IMPORTS = [
+        """from eth2spec.bellatrix.mainnet import (
+            Attestation,
+            AttesterSlashing,
+            BLSPubkey,
+            BLSSignature,
+            Deposit,
+            DomainType,
+            Eth1Data,
+            ExecutionAddress,
+            ExecutionPayloadHeader,
+            MAX_ATTESTATIONS,
+            MAX_ATTESTER_SLASHINGS,
+            MAX_DEPOSITS,
+            MAX_PROPOSER_SLASHINGS,
+            MAX_VOLUNTARY_EXITS,
+            ProposerSlashing,
+            Root,
+            SignedVoluntaryExit,
+            Slot,
+            SyncAggregate,
+            ValidatorIndex
+        )""",
+        "from eth2spec.utils.ssz.ssz_typing import (Bytes32, Container, List, uint64, uint256)"
+]
+
+CAPELLA_IMPORTS = ["from eth2spec.capella.mainnet import SignedBLSToExecutionChange"]
+
+if __name__ == "__main__":
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--specs", dest="specs", nargs="+", type=Path)
+    args = parser.parse_args()
+
+    specs = args.specs
+    files = [spec_files(spec) for spec in specs]
+    spec = SpecObject(functions={}, custom_types={}, constant_vars={}, ssz_objects={})
+    for (spec_name, spec_files) in zip(specs, files):
+        latest_spec = build_spec(spec_files)
+        spec = combine_specs(spec, latest_spec)
+        dst = os.path.join("tests", "core", "pyspec", "builderspec")
+        with open(os.path.join(dst, f"{spec_name}.py"), "w") as f:
+            spec_src = object_to_spec(spec)
+
+            spec_imports = []
+            if str(spec_name) == "bellatrix":
+                spec_imports = BELLATRIX_IMPORTS
+            elif str(spec_name) == "capella":
+                spec_imports = BELLATRIX_IMPORTS
+                for imp in CAPELLA_IMPORTS:
+                    spec_imports.append(imp)
+
+            spec_imports = "\n".join(spec_imports)
+            spec_src = "\n\n".join([spec_imports, spec_src])
+
+            f.write(spec_src)
+        with open(os.path.join(dst, "__init__.py"), "w") as f:
+            pass
diff --git a/tests/core/pyspec/builderspec/__init__.py b/tests/core/pyspec/builderspec/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/core/pyspec/builderspec/test/__init__.py b/tests/core/pyspec/builderspec/test/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/core/pyspec/builderspec/test/bellatrix/__init__.py b/tests/core/pyspec/builderspec/test/bellatrix/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/core/pyspec/builderspec/test/bellatrix/test_bid.py b/tests/core/pyspec/builderspec/test/bellatrix/test_bid.py
new file mode 100644
index 0000000..a74e6fa
--- /dev/null
+++ b/tests/core/pyspec/builderspec/test/bellatrix/test_bid.py
@@ -0,0 +1,4 @@
+from builderspec.bellatrix import BuilderBid
+
+def test_bid():
+    bid = BuilderBid()