I applaud your ambitiousness. Unfortunately, everything that you mentioned makes this a non-starter.
1) 6000 lumen output = not happening for the reasons many have already mentioned
2) Making two headlamps for $155 when you have no tools = not happening because you will need tools and they are not cheap
3) Making a waterproof DIY headlamp of any output level with no prior electronics experience or tools = not happening
Point #3 can be overcome if you are willing to spend money on tools and supplies and are willing to invest significant time in learning through research and personal trial and error. This will likely take hundreds of dollars for tools and materials and at least a month of investing all of your spare time. I don’t know if that is something that you would want.
Here’s a DIY caving lamp made by a BLF member: Just made a helmet lamp
It uses a simple design made with inexpensive prefab parts, but still it is clear that a tremendous amount of time and ingenuity had to go into it.