diff --git a/config/minimal.yaml b/config/minimal.yaml
new file mode 100644
index 0000000..78cd601
--- /dev/null
+++ b/config/minimal.yaml
@@ -0,0 +1,156 @@
+# Minimal preset
+
+
+# Misc
+# ---------------------------------------------------------------
+
+# [customized] Just 4 committees for slot for testing purposes
+MAX_COMMITTEES_PER_SLOT: 4
+# [customized] unsecure, but fast
+TARGET_COMMITTEE_SIZE: 4
+# 2**11 (= 2,048)
+MAX_VALIDATORS_PER_COMMITTEE: 2048
+# 2**2 (= 4)
+MIN_PER_EPOCH_CHURN_LIMIT: 4
+# 2**16 (= 65,536)
+CHURN_LIMIT_QUOTIENT: 65536
+# [customized] Faster, but unsecure.
+SHUFFLE_ROUND_COUNT: 10
+# [customized]
+MIN_GENESIS_ACTIVE_VALIDATOR_COUNT: 64
+# Jan 3, 2020
+MIN_GENESIS_TIME: 1578009600
+# 4
+HYSTERESIS_QUOTIENT: 4
+# 1 (minus 0.25)
+HYSTERESIS_DOWNWARD_MULTIPLIER: 1
+# 5 (plus 1.25)
+HYSTERESIS_UPWARD_MULTIPLIER: 5
+
+
+
+# Fork Choice
+# ---------------------------------------------------------------
+# 2**1 (= 1)
+SAFE_SLOTS_TO_UPDATE_JUSTIFIED: 2
+
+
+# Validator
+# ---------------------------------------------------------------
+# [customized] process deposits more quickly, but insecure
+ETH1_FOLLOW_DISTANCE: 16
+# 2**4 (= 16)
+TARGET_AGGREGATORS_PER_COMMITTEE: 16
+# 2**0 (= 1)
+RANDOM_SUBNETS_PER_VALIDATOR: 1
+# 2**8 (= 256)
+EPOCHS_PER_RANDOM_SUBNET_SUBSCRIPTION: 256
+# 14 (estimate from Eth1 mainnet)
+SECONDS_PER_ETH1_BLOCK: 14
+
+
+# Deposit contract
+# ---------------------------------------------------------------
+# Ethereum Goerli testnet
+DEPOSIT_CHAIN_ID: 5
+DEPOSIT_NETWORK_ID: 5
+# **TBD**
+DEPOSIT_CONTRACT_ADDRESS: 0x1234567890123456789012345678901234567890
+
+
+# Gwei values
+# ---------------------------------------------------------------
+# 2**0 * 10**9 (= 1,000,000,000) Gwei
+MIN_DEPOSIT_AMOUNT: 1000000000
+# 2**5 * 10**9 (= 32,000,000,000) Gwei
+MAX_EFFECTIVE_BALANCE: 32000000000
+# 2**4 * 10**9 (= 16,000,000,000) Gwei
+EJECTION_BALANCE: 16000000000
+# 2**0 * 10**9 (= 1,000,000,000) Gwei
+EFFECTIVE_BALANCE_INCREMENT: 1000000000
+
+
+# Initial values
+# ---------------------------------------------------------------
+# Highest byte set to 0x01 to avoid collisions with mainnet versioning
+GENESIS_FORK_VERSION: 0x00000001
+BLS_WITHDRAWAL_PREFIX: 0x00
+
+
+# Time parameters
+# ---------------------------------------------------------------
+# [customized] Faster to spin up testnets, but does not give validator reasonable warning time for genesis
+GENESIS_DELAY: 300
+# [customized] Faster for testing purposes
+SECONDS_PER_SLOT: 6
+# 2**0 (= 1) slots 6 seconds
+MIN_ATTESTATION_INCLUSION_DELAY: 1
+# [customized] fast epochs
+SLOTS_PER_EPOCH: 8
+# 2**0 (= 1) epochs
+MIN_SEED_LOOKAHEAD: 1
+# 2**2 (= 4) epochs
+MAX_SEED_LOOKAHEAD: 4
+# [customized] higher frequency new deposits from eth1 for testing
+EPOCHS_PER_ETH1_VOTING_PERIOD: 4
+# [customized] smaller state
+SLOTS_PER_HISTORICAL_ROOT: 64
+# 2**8 (= 256) epochs
+MIN_VALIDATOR_WITHDRAWABILITY_DELAY: 256
+# [customized] higher frequency of committee turnover and faster time to acceptable voluntary exit
+SHARD_COMMITTEE_PERIOD: 64
+# [customized] fast catchup crosslinks
+MAX_EPOCHS_PER_CROSSLINK: 4
+# 2**2 (= 4) epochs
+MIN_EPOCHS_TO_INACTIVITY_PENALTY: 4
+
+
+# State vector lengths
+# ---------------------------------------------------------------
+# [customized] smaller state
+EPOCHS_PER_HISTORICAL_VECTOR: 64
+# [customized] smaller state
+EPOCHS_PER_SLASHINGS_VECTOR: 64
+# 2**24 (= 16,777,216) historical roots
+HISTORICAL_ROOTS_LIMIT: 16777216
+# 2**40 (= 1,099,511,627,776) validator spots
+VALIDATOR_REGISTRY_LIMIT: 1099511627776
+
+
+# Reward and penalty quotients
+# ---------------------------------------------------------------
+# 2**6 (= 64)
+BASE_REWARD_FACTOR: 64
+# 2**9 (= 512)
+WHISTLEBLOWER_REWARD_QUOTIENT: 512
+# 2**3 (= 8)
+PROPOSER_REWARD_QUOTIENT: 8
+# 2**24 (= 16,777,216)
+INACTIVITY_PENALTY_QUOTIENT: 16777216
+# 2**5 (= 32)
+MIN_SLASHING_PENALTY_QUOTIENT: 32
+
+
+# Max operations per block
+# ---------------------------------------------------------------
+# 2**4 (= 16)
+MAX_PROPOSER_SLASHINGS: 16
+# 2**1 (= 2)
+MAX_ATTESTER_SLASHINGS: 2
+# 2**7 (= 128)
+MAX_ATTESTATIONS: 128
+# 2**4 (= 16)
+MAX_DEPOSITS: 16
+# 2**4 (= 16)
+MAX_VOLUNTARY_EXITS: 16
+
+
+# Signature domains
+# ---------------------------------------------------------------
+DOMAIN_BEACON_PROPOSER: 0x00000000
+DOMAIN_BEACON_ATTESTER: 0x01000000
+DOMAIN_RANDAO: 0x02000000
+DOMAIN_DEPOSIT: 0x03000000
+DOMAIN_VOLUNTARY_EXIT: 0x04000000
+DOMAIN_SELECTION_PROOF: 0x05000000
+DOMAIN_AGGREGATE_AND_PROOF: 0x06000000
diff --git a/lib/beacon_state.py b/lib/beacon_state.py
new file mode 100644
index 0000000..ea46a8e
--- /dev/null
+++ b/lib/beacon_state.py
@@ -0,0 +1,34 @@
+from enum import auto, Enum
+
+
+class BeaconState(Enum):
+    DEFAULT = auto()
+
+
+# NOTE: when network_config is specifiable, it needs to be an arg here
+def default_builder():
+    from eth2spec.config.config_util import prepare_config
+    prepare_config('config', 'minimal')
+
+    from eth2spec.phase0.spec import initialize_beacon_state_from_eth1
+    from eth2spec.test.helpers.deposits import prepare_genesis_deposits
+
+    import eth2fastspec as spec
+
+    deposits, deposit_root, _ = prepare_genesis_deposits(
+        spec, spec.MIN_GENESIS_ACTIVE_VALIDATOR_COUNT, spec.MAX_EFFECTIVE_BALANCE, signed=True)
+
+    eth1_block_hash = b'\x12' * 32
+    eth1_timestamp = spec.MIN_GENESIS_TIME
+    state = initialize_beacon_state_from_eth1(eth1_block_hash, eth1_timestamp, deposits)
+
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    with open(path, 'wb') as w:
+        state.serialize(w)
+
+    return state
+
+
+BEACON_STATE_BUILDERS = {
+    BeaconState.DEFAULT: default_builder
+}
diff --git a/setup.py b/setup.py
index 44b0b29..5cea5a8 100644
--- a/setup.py
+++ b/setup.py
@@ -21,6 +21,8 @@
         "PyYAML==5.3.1",
         "ansicolors==1.1.8",
         "eth-utils==1.8.4",
+        "eth2spec>=0.12.2",
+        "eth2fastspec==0.0.5"
     ],
     classifiers=[
         "Programming Language :: Python :: 3",