e discovered Makelastic during our experimentation. We discovered that a certain mixture of Ethyl lactate and other alcohols was a very effective plasticizer, getting in-between the PLA molecules and loosening their bonds. Suddenly, you didn't have to mess around with flexible filaments - good ol' reliable PLA could be used and then rubberized! Best of all, Makelastic was safer than even Acetone. For example, Ethyl Lactate is commonly used in fragrances - it has a scent that is close to coconuts (we kid you not).
Makelastic tends to dissipate over a few months, necessitating a quick spray with any off-the-shelf polyurethane spray. So far our prints have remained flexible!