For Ulitimakers, it's a given, their website. But, the guides especially for the Ultimaker 3 are great! It teaches you how to do everything, and for all of us tinkerers, it's an interesting read, these machines have so many components and technology, it's amazing! Also, the Cura software is open source, while a bit simplified, it's great! Ultimaker has great resources and interesting designs that I recommend anyone who enjoys 3-D printing reads, its a great example of open design, software, help, and general coolness!