This started as a cost saving project to make a better flame weeder than what was available for purchase for "just" the cost of materials. This project just like many took more time and materials than expected. The biggest thing I would say to anyone taking something like this on is that the wheels need to be further away from the flame than you might think. When used outdoors the intense flame is blown around and in addition to heating the operator it sends a lot of heat to the tires.
For the stainless steel used to make the hood, TIG welding was a good solution/tool for the job, however, for the rest of the frame a MIG welder would have been much easier. Welding in a green house with any draft is hard with TIG because you lose your gas shielding and your welds don't turn out happy.
Materials used were purchased on eBay and amazon. The torch heads were Red Dragon 250K BTU heads by Flame Engineering, which accept a 1/4" NPT pipe, some that was not documented very well. The threaded bungs that were welded into the gas manifold were ordered from bungking.com great for DIY threaded things.
More hindsight, I would not have welded up the gas manifold if I were doing it again, iron pipe would be just fine. The only challenging part would be the attachment of the hood to the pipe. I intentionally did not use the burners as a mounting point to make them easily replaceable if needed. The tank mounting turned out better than expected, just using 5/8" rod to make a triangle to hold it in place. No need for an additional cords or clamps.
Oh yeah, the damn kick stand, in the original configuration I made a little stand so that it could rest with the burners off the ground when not in use or cooling off. This was a mistake, this little piece ended up dragging through the row damaging plants. This "feature" was quickly cut off.
Handles, while a seemly simple part of this project, they proved to be hard to do "right". It would seem that the wider or closer to the wheels they are mounted the better the tool will behave. I started with a smaller handle and it was mounted towards the center of weeder, this made it extremely difficult to push or steer. Bigger wheels would have also been better for the rocky New England Soil.