Enjoyable, thanks. I thought I was listening to Noaaaurm on This Old House. when they spoke.
Question, why TIG first for the tack, then come back with MIG? I doubt any serious heat would occur with a MIG tack and cause a shift, but then again, what do I know.
The TIG has better heat control, less distortion. You get rolling with MIG the total heat builds pretty fast, sheet metal will distort.
My experience tacking the bottom half of a door skin. Using a MIG machine, first tack in the middle, then one at each end. Then halfing distances on each side. Welding on both sides of the middle tack. Still had to stop let things cool, and did get distortion.
He got that piece knocked out really quick with almost zero distortion. Dam good trick, just think how the finish looked. And what little time getting there.
To me I could see @ most high build primer and a quick blocking ........... to perfection.
That boy has some talent, I'll say.