I'm with you on the development side of things.
I've made my own now, and can see that there are a number of variables.
The positioning of the spring
The length of the spring
The angle of the tube that receives the Harris pole
The position of the draw string
Whether to use rivets or machine screws in the various locations.
But I think there's some potential for this thing - limited, yes, but I can think of a few uses.
There is always room for improvement

Don't use a powerful spring, the reason for the spring is to just reopen the grabbers, so you don't have to lower it to open them back up.
You can see rivets on mine also 1 self tapping screw, the hole below this screw is a curved shape to allow the grabbers to swing open, if you put in a straight line of holes then the screw can bind and stop free movement.
My main reason for it is to just grab items out of gutters, my Mk1 is the best for getting Gardens out of the gutters.
Lets see your pictures of it then Mr Tumble.