It depends entirely on what you use to raise it. Creating Steel Dragons over and over again would be insanley fast XP, albeit slightly costly. In my opinion the most efficient way of training construction is with oak planks, making oak larders with the aid of a butler. Eack Oak Plank used yields 60xp, and the current market value of them appears to be 500each (at a quick glance). 200,000,000 (Target XP) / 60 (Oak Planks XP) = 3,333,333.333... (Oak Planks). So we know you'll need 3,333,334 Oak Planks for 200m XP, times that by the cost of them: 3,333,334 * 500 = 1,666,667,000. If my calculations are right (and they probably aren't :oops: ) it would cost around 1.67B GP for 200M Construction XP, that isn't accounting the costs of your Demon Butler (those 10k fees would start to add up). Bear in mind that's for one skill only, out of a current 22. Prayer would have a similar sort of price tag to max out. Technically it is possible to achieve 200m in every skill, but it would take vast amounts of money and more importantly time; which I don't think anyone has that much of. (Also as a little side note, along the way more skills are bound to be released, maybe some as slow as Slayer; that won't help a great deal either...) So I would say technically YES, you could do it, but physically doing it is a completely different task...