ReCraft

ReCraft is a blockchain-powered sustainability marketplace that transforms waste into economic opportunity. We connect institutions (schools, colleges, offices) with NGOs and artisans to convert discarded paper and materials into sustainable home décor products, creating a complete traceability chain from donation to final sale.

The Problem: 65 million tons of institutional paper waste annually, while NGOs and artisans struggle with income transparency and fair compensation. Traditional recycling markets lack verifiable supply chains and equitable revenue distribution.

Our Solution: A trustless ecosystem where every donation is recorded on-chain, product journeys are fully traceable, and revenue distribution is automated via smart contracts—70% to NGOs/artisans, 20% to donating institutions, 10% to platform. No intermediaries, no payment delays, complete transparency.

Key Innovation: We integrate Avail Nexus for cross-chain payments (enabling users to pay with ETH from Optimism, Arbitrum, or Base Sepolia and automatically bridge + execute purchases on Ethereum Sepolia) and PayPal USD (PYUSD) for stablecoin transactions, removing price volatility and enabling global participation.

Core Features:

• Cross-Chain Bridge & Execute - Pay from any supported chain, funds automatically bridge and purchase in one transaction
• Dual Payment System - Accept both native ETH and PYUSD stablecoin
• On-Chain Traceability - Every donation, product, and sale verifiable via smart contract events
• Automated Revenue Split - Smart contract enforces 70/20/10 distribution instantly
• Public Verification - Anyone can verify product journey from source institution to final buyer
• Multi-Wallet Support - ConnectKit integration with MetaMask, WalletConnect, Coinbase Wallet

Real-World Impact:

• Environmental: Diverts thousands of tons of paper waste from landfills
• Social: Creates fair-income opportunities for underserved artisan communities
• Economic: Transparent, immutable revenue distribution builds trust in circular economy
• Technical: Demonstrates practical DeFi utility beyond speculation

ReCraft is built as a full-stack Web3 application combining Solidity smart contracts on Ethereum Sepolia, cross-chain bridging via Avail Nexus, PYUSD stablecoin integration, and a React frontend with Wagmi and ConnectKit.

Smart Contracts (Solidity ^0.8.20): Deployed on Ethereum Sepolia via Remix IDE with full verification. Core functions include createDonation() for institutions to record waste materials on-chain, acceptDonation() for NGOs to claim materials, createProduct() linking crafted items to source donations for traceability, and dual purchase functions—purchaseProductWithETH() and purchaseProductWithPYUSD()—both automatically executing 70/20/10 revenue splits. We use OpenZeppelin libraries for security, reentrancy guards on all payment functions, and access control to ensure only authorized NGOs can claim donations.

Avail Nexus Integration: We integrated @avail-project/nexus-core SDK (v0.0.2-beta.7) to enable cross-chain payments. Users can pay with ETH from Optimism Sepolia, Arbitrum Sepolia, or Base Sepolia, and the SDK automatically bridges funds to Ethereum Sepolia while executing the product purchase in a single atomic transaction. The implementation uses nexusSdk.bridgeAndExecute() with our smart contract's purchaseProductWithETH() as the execute parameter. We built a custom CrossChainPurchaseWidget component that simulates transactions before execution, showing users exact costs (product price + bridge fees + gas). Key challenge: Initially encountered a bug bridging to Sepolia, reached out to Avail team on Discord, and they quickly released an updated beta that fixed the issue—excellent sponsor support during development.

PayPal USD (PYUSD) Integration: Integrated PYUSD stablecoin (ERC-20 on Sepolia) to provide price stability for users avoiding ETH volatility. Our smart contract includes a dedicated purchaseProductWithPYUSD() function that handles ERC-20 transfers and distributes revenue in PYUSD to all parties. The frontend converts product prices from ETH to USD, handles the two-step approval flow (approve PYUSD spend, then purchase), and provides clear UX for the approval process. Why PYUSD? Many NGOs and artisans in developing regions prefer stable currencies—PYUSD enables predictable revenue without crypto volatility, making ReCraft globally accessible.

Frontend (React + Vite + Wagmi): Built with React 18, Wagmi v2 for Web3 hooks, ConnectKit for wallet UI, and TailwindCSS. Features include a responsive marketplace with real-time filtering, cross-chain payment widget with live simulation, product traceability views showing source-to-sale journey, and separate dashboards for institutions (donation management) and NGOs (product creation and artisan management). The app supports multiple wallets and automatically switches users to Sepolia network when needed.

Backend (Node.js + Express + MongoDB): Handles off-chain data storage for user profiles, product metadata, and donation details, synced with on-chain records. JWT authentication for role-based access (institutions vs NGOs vs buyers), MongoDB for flexible data models, and REST API endpoints for registration, product listings, and blockchain data verification.

Technical Innovations:

• Cross-chain UX: Users don't need to manually bridge or hold multiple tokens—Nexus handles everything in one transaction
• Dual payment rails: Native ETH for crypto users, PYUSD for stability-seekers On-chain revenue enforcement: Smart contract automatically splits payments, no trust required
• Real-time simulation: Shows exact costs before executing cross-chain transactions
• Traceability system: Complete product journey verifiable on-chain from donation to sale

Hacky Bits: Avail Nexus SDK updated mid-development (beta.5 → beta.7), requiring us to adapt how we pass value and buildFunctionParams—ultimately cleaner code. Built debounced simulation engine to show real-time costs without hitting rate limits. Smart contract uses integer math for percentage splits (basis points) to avoid floating-point errors in revenue distribution.

Why This Stack? Avail Nexus removes cross-chain friction, PYUSD provides stability for artisans, Wagmi + ConnectKit offers excellent DX, and MongoDB enables rapid iteration. ReCraft demonstrates how DeFi primitives (bridging, stablecoins, smart contract automation) can solve real environmental and social problems beyond financial speculation.