No more than say, building a model airplane or model car. The movements for these watches especially are relatively cheap - you can find plenty of 7S26s on ebay for right around $20-25 - so the cost of replacing one that you might mess up is low. i recently rebuilt a similar movement with no prior experience and am actually wearing the watch right now. The best tool to have is a loupe, a good set of tweezers, and patience!