diff --git a/Makefile b/Makefile
index 2ddc82e68..a262ac5e1 100644
--- a/Makefile
+++ b/Makefile
@@ -67,11 +67,11 @@ phase0: $(PY_SPEC_PHASE_0_TARGETS)
 # "make phase1" to create pyspec for phase1
 phase1: $(PY_SPEC_PHASE_1_TARGETS)
 
-$(PY_SPEC_DIR)/eth2spec/phase0/spec.py: $(PY_SPEC_PHASE_0_DEPS)
-	python3 $(SCRIPT_DIR)/phase0/build_spec.py  $(SPEC_DIR)/core/0_beacon-chain.md $@
+$(PY_SPEC_PHASE_0_TARGETS): $(PY_SPEC_PHASE_0_DEPS)
+	python3 $(SCRIPT_DIR)/build_spec.py -p0 $(SPEC_DIR)/core/0_beacon-chain.md $@
 
 $(PY_SPEC_DIR)/eth2spec/phase1/spec.py: $(PY_SPEC_PHASE_1_DEPS)
-	python3 $(SCRIPT_DIR)/phase0/build_spec.py -p1  $(SPEC_DIR)/core/1_custody-game.md $@
+	python3 $(SCRIPT_DIR)/build_spec.py -p1 $(SPEC_DIR)/core/0_beacon-chain.md $(SPEC_DIR)/core/1_custody-game.md $@
 
 CURRENT_DIR = ${CURDIR}
 
diff --git a/scripts/phase0/__init__.py b/scripts/__init__.py
similarity index 100%
rename from scripts/phase0/__init__.py
rename to scripts/__init__.py
diff --git a/scripts/build_spec.py b/scripts/build_spec.py
new file mode 100644
index 000000000..c77a8b82f
--- /dev/null
+++ b/scripts/build_spec.py
@@ -0,0 +1,196 @@
+import sys
+import re
+import function_puller
+from argparse import ArgumentParser
+from typing import Tuple, List
+
+
+def split_retain_delimiter(regex_pattern: str, text: str) -> List[str]:
+    '''
+    Splits a string based on regex, but down not remove the matched text
+    '''
+    find_pattern = r'%s.*?(?=%s|$)' % (regex_pattern, regex_pattern)
+    return re.findall(find_pattern, text, re.DOTALL)
+
+
+def inserter(oldfile: str, newfile: str) -> Tuple[str, str]:
+    '''
+    Searches for occurrences of @LabelName in oldfile and replaces them with instances of code wraped as follows:
+    # begin insert @LabelName
+    def foo(bar):
+        return bar
+    # end insert @LabelName
+    '''
+    new_insert_objects = re.split(r"(# begin insert |# end insert @[a-zA-Z0-9_]*\n)", newfile)
+    # Retrieve label from insert objects
+    def get_labeled_object(labeled_text):
+        label = re.match(r"@[a-zA-Z0-9_]*\n", labeled_text)
+        if label is not None:
+            label = label.group(0)
+            labeled_text = re.sub(label, '', labeled_text)            
+        return {'label': label, 'text': labeled_text}
+    new_insert_objects = map(get_labeled_object, new_insert_objects)
+    # Find and replace labels
+    newfile = ""
+    for item in new_insert_objects:
+        if item['label'] is not None:
+            oldfile, insertions = re.subn('# %s' % item['label'], item['text'], oldfile)
+            if insertions == 0:
+                newfile.join('# begin insert %s/n%s# end insert %s' % (item['label'], item['text'], item['label']))
+        elif re.match(r"(# begin insert |# end insert )", item['text']) is None:
+            newfile += item['text']
+    return oldfile, newfile
+
+
+def merger(oldfile:str, newfile:str) -> str:
+    '''
+    Seeks out functions and objects in new and old files.
+    Replaces old objects with new ones if they exist.
+    '''
+    old_objects = split_retain_delimiter('\n[a-zA-Z]', oldfile)
+    new_objects = split_retain_delimiter('\n[a-zA-Z]', newfile)
+    object_regex = r"\n[#@a-zA-Z_0-9]+[\sa-zA-Z_0-9]*[(){}=:'" "]*"
+    old_object_tuples = list(map(lambda x: [re.match(object_regex, x).group(0),x], old_objects))
+    for new_item in new_objects:
+        found_old = False
+        for old_item in old_object_tuples:            
+            if old_item[0] == re.match(object_regex, new_item).group(0):
+                print(old_item[0])
+                old_item[1] = new_item
+                found_old = True
+                break
+        if not found_old:
+            old_object_tuples += [[re.match(object_regex, new_item).group(0), new_item]]
+    return ''.join(elem for elem in map(lambda x: x[1], old_object_tuples))
+
+
+def build_phase0_spec(sourcefile, outfile=None):
+    code_lines = []
+    code_lines.append("""
+
+from typing import (
+    Any,
+    Dict,
+    List,
+    NewType,
+    Tuple,
+)
+from eth2spec.utils.minimal_ssz import (
+    SSZType,
+    hash_tree_root,
+    signing_root,
+)
+from eth2spec.utils.bls_stub import (
+    bls_aggregate_pubkeys,
+    bls_verify,
+    bls_verify_multiple,
+)
+from eth2spec.utils.hash_function import hash
+
+
+# stub, will get overwritten by real var
+SLOTS_PER_EPOCH = 64
+
+Slot = NewType('Slot', int)  # uint64
+Epoch = NewType('Epoch', int)  # uint64
+Shard = NewType('Shard', int)  # uint64
+ValidatorIndex = NewType('ValidatorIndex', int)  # uint64
+Gwei = NewType('Gwei', int)  # uint64
+Bytes32 = NewType('Bytes32', bytes)  # bytes32
+BLSPubkey = NewType('BLSPubkey', bytes)  # bytes48
+BLSSignature = NewType('BLSSignature', bytes)  # bytes96
+Store = None
+""")
+
+    code_lines += function_puller.get_spec(sourcefile)
+
+    code_lines.append("""
+# Monkey patch validator compute committee code
+_compute_committee = compute_committee
+committee_cache = {}
+
+
+def compute_committee(indices: List[ValidatorIndex], seed: Bytes32, index: int, count: int) -> List[ValidatorIndex]:
+    param_hash = (hash_tree_root(indices), seed, index, count)
+
+    if param_hash in committee_cache:
+        return committee_cache[param_hash]
+    else:
+        ret = _compute_committee(indices, seed, index, count)
+        committee_cache[param_hash] = ret
+        return ret
+
+
+# Monkey patch hash cache
+_hash = hash
+hash_cache = {}
+
+
+def hash(x):
+    if x in hash_cache:
+        return hash_cache[x]
+    else:
+        ret = _hash(x)
+        hash_cache[x] = ret
+        return ret
+
+
+# Access to overwrite spec constants based on configuration
+def apply_constants_preset(preset: Dict[str, Any]):
+    global_vars = globals()
+    for k, v in preset.items():
+        global_vars[k] = v
+
+    # Deal with derived constants
+    global_vars['GENESIS_EPOCH'] = slot_to_epoch(GENESIS_SLOT)
+
+    # Initialize SSZ types again, to account for changed lengths
+    init_SSZ_types()
+""")
+
+    if outfile is not None:
+        with open(outfile, 'w') as out:
+            out.write("\n".join(code_lines))
+    else:
+        return "\n".join(code_lines)
+
+
+def build_phase1_spec(phase0_sourcefile, phase1_sourcefile, outfile=None):
+    phase0_code = build_phase0_spec(phase0_sourcefile)
+    phase1_code = build_phase0_spec(phase1_sourcefile)
+    phase0_code, phase1_code = inserter(phase0_code, phase1_code)
+    phase1_code = merger(phase0_code, phase1_code)
+    
+    if outfile is not None:
+        with open(outfile, 'w') as out:
+            out.write(phase1_code)
+    else:
+        return phase1_code
+
+
+if __name__ == '__main__':
+    description = '''
+Build the specs from the md docs.
+If building phase 0:
+    1st argument is input spec.md 
+    2nd argument is output spec.py
+
+If building phase 1:
+    1st argument is input spec_phase0.md 
+    2nd argument is input spec_phase1.md 
+    3rd argument is output spec.py
+'''
+    parser = ArgumentParser(description=description)
+    parser.add_argument("-p", "--phase", dest="phase", type=int, default=0, help="Build for phase #")
+    parser.add_argument(dest="files", help="Input and output files", nargs="+")
+
+    args = parser.parse_args()
+    if args.phase == 0:
+        build_phase0_spec(*args.files)
+    elif args.phase == 1:
+        if len(args.files) == 3:
+            build_phase1_spec(*args.files)
+        else:
+            print(" Phase 1 requires an output as well as 2 input files (phase0.md and phase1.md)")
+    else:
+        print("Invalid phase: {0}".format(args.phase))
diff --git a/scripts/phase0/function_puller.py b/scripts/function_puller.py
similarity index 100%
rename from scripts/phase0/function_puller.py
rename to scripts/function_puller.py
diff --git a/scripts/phase0/build_spec.py b/scripts/phase0/build_spec.py
deleted file mode 100644
index 4faf8cbf6..000000000
--- a/scripts/phase0/build_spec.py
+++ /dev/null
@@ -1,143 +0,0 @@
-import sys
-import function_puller
-from optparse import OptionParser
-
-def build_phase0_spec(sourcefile, outfile):
-    code_lines = []
-    code_lines.append("""
-
-from typing import (
-    Any,
-    Dict,
-    List,
-    NewType,
-    Tuple,
-)
-from eth2spec.utils.minimal_ssz import (
-    SSZType,
-    SSZTypeExtension,
-    hash_tree_root,
-    signing_root,
-)
-from eth2spec.utils.bls_stub import (
-    bls_aggregate_pubkeys,
-    bls_verify,
-    bls_verify_multiple,
-)
-from eth2spec.utils.hash_function import hash
-
-
-# stub, will get overwritten by real var
-SLOTS_PER_EPOCH = 64
-
-Slot = NewType('Slot', int)  # uint64
-Epoch = NewType('Epoch', int)  # uint64
-Shard = NewType('Shard', int)  # uint64
-ValidatorIndex = NewType('ValidatorIndex', int)  # uint64
-Gwei = NewType('Gwei', int)  # uint64
-Bytes32 = NewType('Bytes32', bytes)  # bytes32
-BLSPubkey = NewType('BLSPubkey', bytes)  # bytes48
-BLSSignature = NewType('BLSSignature', bytes)  # bytes96
-Store = None
-""")
-
-    code_lines += function_puller.get_spec(sourcefile)
-
-    code_lines.append("""
-# Monkey patch validator compute committee code
-_compute_committee = compute_committee
-committee_cache = {}
-
-
-def compute_committee(indices: List[ValidatorIndex], seed: Bytes32, index: int, count: int) -> List[ValidatorIndex]:
-    param_hash = (hash_tree_root(indices), seed, index, count)
-
-    if param_hash in committee_cache:
-        return committee_cache[param_hash]
-    else:
-        ret = _compute_committee(indices, seed, index, count)
-        committee_cache[param_hash] = ret
-        return ret
-
-
-# Monkey patch hash cache
-_hash = hash
-hash_cache = {}
-
-
-def hash(x):
-    if x in hash_cache:
-        return hash_cache[x]
-    else:
-        ret = _hash(x)
-        hash_cache[x] = ret
-        return ret
-
-
-# Access to overwrite spec constants based on configuration
-def apply_constants_preset(preset: Dict[str, Any]):
-    global_vars = globals()
-    for k, v in preset.items():
-        global_vars[k] = v
-
-    # Deal with derived constants
-    global_vars['GENESIS_EPOCH'] = slot_to_epoch(GENESIS_SLOT)
-
-    # Initialize SSZ types again, to account for changed lengths
-    init_SSZ_types()
-""")
-
-    with open(outfile, 'w') as out:
-        out.write("\n".join(code_lines))
-
-
-def build_phase1_spec(sourcefile, outfile):
-    code_lines = []
-    code_lines.append("""
-from eth2spec.phase0.spec import *
-from eth2spec.phase0.spec import apply_constants_preset as apply_constants_preset_phase0
-
-""")
-
-    code_lines += function_puller.get_spec(sourcefile)
-
-    code_lines.append("""
-# Access to overwrite spec constants based on configuration
-def apply_constants_preset(preset: Dict[str, Any]):
-
-    apply_constants_preset_phase0(preset)
-
-    global_vars = globals()
-    for k, v in preset.items():
-        global_vars[k] = v
-
-    # Deal with derived constants
-    global_vars['GENESIS_EPOCH'] = slot_to_epoch(GENESIS_SLOT)
-
-    # Initialize SSZ types again, to account for changed lengths
-    init_SSZ_types()
-""")
-
-    with open(outfile, 'w') as out:
-        out.write("\n".join(code_lines))
-
-
-if __name__ == '__main__':
-    parser = OptionParser()
-    parser.add_option("-p", "--phase", dest="phase", type="int", default=0,
-                  help="Build for phase #")
-
-    (options, args) = parser.parse_args()
-
-    if len(args) < 2:
-        parser.print_help()
-    
-    if options.phase == 0:
-        build_phase0_spec(args[0], args[1])
-        print(args[0])
-        print(args[1])
-    elif options.phase == 1:
-        build_phase1_spec(args[0], args[1])
-    else:
-        print("Invalid phase: {0}".format(options["phase"]))
-