I'm building my Kossel Pro kit right now. The quality of the parts and the engineering appear outstanding. The big disappointment is the lack of good instructions. No, that's an understatement. The instructions are a disaster. I like the concept of instructions they use, which is a series of online Powerpoint presentations with text and pictures to walk you through each element of the build. Easy to update so that everyone always has the most current and complete instructions. Unfortunately, that feature doesn't appear to be in use.