I have wanted a 29er mountain bike for a while and stumbled across an old Trek 720 hybrid that I was going to just fix up to make into a commuter bike but was inspired. I had many parts around my shop and what you have will dictate where you can take this. For those of you unfamiliar with a 29er, it is a mountain bicycle with 700c wheels (like that of a hybrid) using a larger tire width making the overall tire size around 29" instead of the typical 26" found on most mountain bikes.
I am a welder with a number of years experience in making goofy creations and sculptures, this is the first really high end bicycle. Producing strong welds is crucial in this project so if your not experienced get someone who is. I used a MIG welder for this and am self taught I can't afford a TIG welder yet and have never taken formal classes but have become fairly proficient over the years.
Step 1: Strip the frame
Step 2: Geometry and Head tube
I measured the geometry and used the geometry from a bicycle made by Salsa as a template for how I would line everything up and weld it together.