by Christoph Rosenmayr and Jascha Samadi – June 10, 2025

We’re excited to announce that Greenfield is participating in nuConstruct’s $6M seed funding round alongside CyberFund, Maven11, DCG, and EdenBlock VC. nuConstruct is developing TOOL, an out-of-protocol solution to scale Ethereum L1 block times from currently 12 seconds to 1 second subslots via early confirmations, which guarantee both inclusion and execution results of transactions. TOOL also improves the market structure in the transaction supply chain, facilitating an annual value flow of over $300M to Ethereum validators. These improvements are crucial to win back market share from competing higher frequency chains.

Ethereum L1 has been drastically losing market share for onchain trading volumes to L2s and competing chains like Solana (while staying dominant in lending and RWAs), mainly as a result of long block times leading to subpar user experience for onchain trading.

This has led to a decline in the value of the average block (recently termed REV), which leads to Validators earning less from execution layer rewards. We think it is important for Ethereum L1 to maintain its role as the main dApp platform and DeFi hub, which includes deep liquidity and onchain trading, to enhance its network effects and keep pace with the competition.

Initial efforts to scale Ethereum L1 have recently started to reemerge – a crucial move to restore trading activity on mainnet. We saw the first gas limit increase since 2021, with further increases seeming likely. However, reducing block times is a separate problem that is harder to solve without impacting current validators and general network health.

Enter TOOL

nuConstruct’s flagship product TOOL (The Trustless Orderflow Operations Layer) introduces early confirmations priced via 1-second subslot auctions. The execution results are shared at the end of each subslot, allowing further subslots to build on said state, effectively achieving a similar UX to 1-second block times on Ethereum L1 without any protocol changes.

To guarantee that validators honor the correct execution of early confirmations, they need to opt into TOOL’s TEE (Trusted Execution Environment) network. It requires not more than a one-line change in their current MEV-boost config to receive blocks with subslots from TOOL rather than from MEV-boost relays as they do currently.

Besides subslots, TOOL aims to introduce default pre-trade privacy for order flow, the ability for dApps to express more granular execution preferences for how they want their transactions to be ordered, and provide roll-ups with atomic synchronous composability via early confirmations.

Additionally, TOOL improves market efficiency by turning the current blind block auction (MEV-boost) into an open auctions by default, which prevents users from overpaying for state access which is common in blind auctions. Additionally, validators’ rewards are increased by allowing them to capture contentious state fees multiple times in the block, as subslots split the auction into twelve 1-second intervals rather than once every 12 seconds.

TOOL will launch on the Hoodi Ethereum testnet in June 2025, with support from the Ethereum Foundation, Coinbase, Figment, Chorus One, and Obol Network. An MVP on Ethereum mainnet is planned to live soon after.

The team behind nuConstruct is uniquely positioned to deliver on this crucial building block for scaling and improving Ethereum L1. They have deep expertise and a track record of successfully competing in Ethereum MEV since 2020, focusing on atomic backrunning and arbitrage, as well as experience working with TEEs for MEV use cases, such as their work with rsync-builder to trustlessly backrun private order flow at the bottom of blocks without requiring trust between searcher and builder.

Get involved

If you are excited about the prospects of having 1-second block times on Ethereum mainnet, are a validator interested in learning about how TOOL can increase block values, or an order flow generator on Ethereum mainnet looking to enrich the value of your flow, follow nuConstruct here or get in touch.