I fugured Mimmo would do this one day. Congratulations if he's pulled it off. "Loading" a string is an ancient technique, and a student of string history like Mimmo would be the one to do it. That old red color is a tip-off.
As a matter of fact, he's done it before. I almost had my hands on a few of the earlier models, but then they were discontinued. From my understanding, this is a very tricky process, with the old formulae lost in the murky medieval history of string-making. There were apparently various methods of impregnating or even gluing metal particles to gut to give it more mass. In the end, winding metal around a gut core turned out to be more reliable, but the gut/particle string (or in this case nylgut variety/particle string) has always been intriguing, because it would have less of a metallic sound than a winding.
The elasticity is puzzling to me, but Mimmo is a bit of a mad scientist (in the best sense), and I imagine he's learned a lot, as he's kept after this for a good while. It would have been nice if the string could have had a slightly higher metal content, and therefore a bit less diameter, but no doubt there are other factors such as bond and tone that have gone into the make-up.
Once again, congratulations, Mimmo!