Sorry, can't make braced slingshots. Totally outlawed. No licenses available.
The slingshot in the picture looks cool, but is probably very heavy and most likely a poor performer, using thick tubular rubber.
Designs like this one are easy if you have a water cutter (flow jet), you just program the shape into the CAM and then the machine will cut it out of an aluminum board within minutes. Without a flow jet, lots of work.
As a lover of machines, tools, and gadgets of all sorts, I can appreciate what draws you (e-shot) to that design, but (as others have noted) it also strikes me as the quintessential Rube Goldberg contraption.
One of the best steampunk slingshot designs I've seen in some time. Design wise it's beautiful in it's own unique way between art and function. At first you wonder what am I looking at? Then the tubes and pouch give it away. Total overkill, and that's cool.
The back half looks like a medical forearm brace with a retro fit slingshot front. It's odd to see a mix-in-match of screws. Most machinists stick with one screw type and use that through out the design. That's what makes me think this is a melding of two different pieces.
I'd like to have seen this completed out where the bands hook to a sled on rails that propels the ammo. Maybe even a simple trigger release. That would take the cake for me.