Hiring a welder to work on a rocket stove charcoal retort. advice apresiated!

First of all love this site, long time lurker first time poster. I am starting work on my hookway style rocket stove charcoal retort. I am in contract with a welder who will be charging me 35$ an hour for welding. I am trying to get some plans together for him so he is prepared and can just dive right into it. I understand the basic concept but without having to fork over 10 pounds for the plans I am having trouble getting it down on paper for him. All the plans I see online are fairly diferent then the hookway concept. Does anyone know of some plans I can provide him? I am working on mine own right now and will post soon to get advice on what needs to be changed. thanks for your time!

ok this is my initial sketch.