Your a welder , stainless steel , or Aluminum , or both , I did not see a close up of the cuff, if it's welded or bolted , or the grab handle .
Good questions. I used stainless steel long-handled scoop to start with. And modified starting with that.
The pistol grip has to be welded on. Which is no easy task, as you know, to weld stainless. I also added more holes in the duck bill to lighten it up. And as you know: Drilling holes in stainless steel is no easy task . You have to have special drill-bits. And even then ... it wears out expensive bits.
As for the arm-cuff location : 2 holes drilled in the stainless steel rod, to make a spot to attach the arm-cuff. The arm-cuff itself is not stainless. That's just regular thick gauge sheet metal, that you can cut and bend to shape. And then, as you can see, I made a bailing wire bridge, over the top of the cuff, that I can slip my arm in-&-out-of.
If you're going to be hunting salt water, then stainless steel is the way to go. Despite it being 3x or 4x more expensive for the raw scoop and rod. Because if you get regular metal, and if you spend a lot of time in the wet salt, then your rig will eventually rot away with rust. Unless you are going to carefully be sure to rinse it off with fresh water after each usage.
Also I noticed that on regular metal non-stainless, that the duck-bill tended to get bent up (if you're on rocky beaches). Versus stainless which keeps its shape better, because it's harder.
I do have a non-stainless rig, With this style arm-cuff mod on it. That I use as a back-up or a loaner. But that was just because I had it lying around, and just did some hole-drilling and adding the pistol grip. Just to have a spare around.