You see, Mattheij decided he wanted in on the profitable cottage industry of online Lego reselling, and after placing a bunch of bids for the colorful little blocks on eBay, he came into possession of 2 tons (4,400 pounds) of Lego -- enough to fill his entire garage. As Mattheij explains in his blog post, resellers can make up to €40 ($45) per kilogram for Lego sets, and rare parts and Lego Technic can fetch up to €100 ($112) per kg. Instead of spending an eternity sifting through his own, intimidatingly large collection, Mattheij set to work on building an automated Lego sorter powered by a neural network that could classify the little building blocks. "By the end of two weeks I had a training data set of 20,000 correctly labeled images."