How would you go about making a rubber dog toy?

I've got a bit of a conundrum. I've got a 10 pound chihuahua whose entire world is a very specific 1.75 inch diameter rubber ball. (And when I say "entire world", I'm understating.) She's gone through a handful of this specific brand and model of rubber ball as old ones have gotten to the point of being too damaged to be safe.

But now the manufacturer has discontinued that line of ball and we're on our last one.

The few other models of rubber balls the same size that I've been able to find have been summarily rejected by the dog. I'm not sure quite what her criteria are for rejecting a ball, even. But I know she'd be a very sad dog indeed if we didn't manage to procure a suitable substitute.

So, at this point, I (and the dog too) am desperate enough to start thinking in terms of maybe crafting a ball as much like the one this dog currently loves to play with.

Of course my primary concern is safety. I wouldn't want pieces of rubber coming off of the final product to be ingested and cause blockages or anything. Nor any danger of blocking an airway.

The ball I'd be apeing is composed of natural rubber. I know you can get liquid latex like this stuff that air dries. Anyone have any idea if that would be suitable for this application? (Or would it be insufficiently durable after drying?)

I've got at my disposal a 3d printer and the skill to design 3d-printable molds. Hopefully the process of molding a ball could avoid heating the mold enough to deform it. I don't have any experience with printing anything but PLA and TPU. But I might be convinced to branch out into ABS or some such if necessary.

I'm just hoping to get some pointers and suggestions. I and my chihuahua thank you all in advance!