Beats me - I've never seen such a mold for sale but I'd imagine they're available or could be designed. I use a lot of dumbbell eyes but never thought to try and cast them. I did try making some larger ones using heavy mono and split shots and this had mixed results, mostly poor.
You might check out some of the companies that make the big molds for conventional gear sinkers or musket balls and contact them directly to see if they have mold for dumbbell eyes.
Let us know if you find something interesting.