Yes, that's what he did. The title makes it seem a bit like he designed the products himself, but the article/video make it pretty clear that he just ordered knock-offs from Alibaba.
>As with Cozy Bag, Chinese manufacturers on Alibaba had been offering comparable products since shortly after the Kickstarter appeared. Thanks to their experience, Jack and his partners were able to pivot quickly and use WordPress and its sales plugin WooComerce to launch their Stress Cube site by the end of November. They spent less than $5,000 on start-up costs, mostly on a bulk order of 1,000 plastic cubes at $3.65 apiece. The plan was to turn around and sell each for $19.99.
>As with Cozy Bag, Chinese manufacturers on Alibaba had been offering comparable products since shortly after the Kickstarter appeared. Thanks to their experience, Jack and his partners were able to pivot quickly and use WordPress and its sales plugin WooComerce to launch their Stress Cube site by the end of November. They spent less than $5,000 on start-up costs, mostly on a bulk order of 1,000 plastic cubes at $3.65 apiece. The plan was to turn around and sell each for $19.99.