Why not learn and build your own cryptos in 2018?! I’ve put together a new free (online) book: Programming Cryptocurrencies and Blockchains in Ruby (Beta / Rough Draft) @ Yuki & Moto Press Bookshelf. The book incl. merkle trees, central banks, shilling, crypto kitties & copycats and, of course, tulips (on the blockchain) :-) and more. Happy new year. Prosit 2018! Cheers.