I bought an os18 with extention last year and it sat in my garage till this year before I started to assemble. I watched a couple of YouTube videos but really didn't need to. The instructions and the way they label the bags and boxes made it super easy to put together. All you need is a few basic hand tools and some time. I have about 12 total hours of assembly time but I'm no ball of fire lol and I did it totally by myself. The machine is built very sturdy and I have no doubt it will provide many years of service. I also need to say how friendly and helpful the staff are especially Stephanie who answered my question and also sent out a part that hadn't received with my order of the extension. Once she found out I had one in my hands in 3 days. That's great service after the sale. If you are on the fence about getting one go ahead, you won't be sorry.