I would like them to do a bigger mold as well, but there are some factors that would have to be considered. First I by no means am the end-all of blade bait design. That said I have been hand cutting and hand pouring blade baits for 30+ years in 1/4 to 1/2 inch increments up to blade baits that look as big as a license plate and 3 ounces. Within all these dozens of lengths and then weights (also varied) I have experimented with countless combinations over the years.
I can tell you that the "Sonar/Silver Buddy" shape that works great for the current 1/2, 5/8, 3/4 sizes, starts to fail in larger sizes. It takes way too much effort to get that vibration out of that shape. I've blown that shape up and there isn't enough surface area.
So once I started getting into bigger blades, a shape and configuration similar to the Zip Lure or Big Dude is much better. In that design I have made huge sizes and weights up to about 3 ounces and they wobble perfectly and easily. In fact a couple guys that I make these monster blades for don't even use Fuzzy Duzzits anymore. Fuzzys need more force and more distance to start to wobble. More tiring....
So, my suggestion is that if Do-It decides to do a bigger blade in heavier sizes, I would have to say for hydrodynamic reasons, the shape of the blade would have to be redesigned. I have prototypes of that original "Large Zonar" mold and the 1 oz. is ok but 1.5 and 2.0 oz. start to lose action without a lot of force and/or speed. Conversely, not enough weight and you get a wildly out of balance lure.
There is a fine line between surface area and weight that will finally kill the action if it gets too heavy. At that point the blade has to get bigger...and on and on... believe me, I have played the game up to about 8 or 9 inch blades and everything in between. Oh and material thickness has to increase too....
Like my fishin buddies say, "don't get him started on blade baits (or Steely Dan)"....
Sorry for the manifesto, I'm a blade nerd. LOL
Marc