well the title says it all ! but i think its very cool since not many people are advertising that method !! i can see some use in it when it comes to tools and many other things !
Well, if I wanted to make a frosted-glass-looking semi-transparent silhouette of a hammerhead shark, I would have just printed it directly with transparent filament.
On the other hand, this is a good proof of a concept, and good to know that if I ever need to make a mold for an epoxy part, I could do it with PETG. A flexible material like TPU would probably be better for printing a mold, and it would likely be re-usable also.