The repurposed red brick warehouse in Manhattan’s Chelsea neighborhood is a bustling hub of modern industrial activity. Skilled young workers are hunched over pristine machine tools and 3-D printers that churn out prototype products.

This is the home of Quirky, a start-up that now fields 4,000 new product ideas a week, picks three winners and then takes over all aspects of production, from making blueprints to marketing the goods through big-box retailers like Home Depot and retail websites, including Amazon.

Most of Quirky’s top-selling products have been inventive, stand-alone devices — like a power strip that pivots so a plug never blocks an adjacent socket, and a plastic stem that inserts into a lemon or lime and becomes a push-button citrus spritzer.

Yet increasingly, the ideas coming into Quirky — about one in four — are for home products that can communicate with a smartphone or a household Wi-Fi network. These are ideas pursuing the much-promoted vision of the smart home, or the consumer Internet of things.