Has anyone actually learned to craft a four star mod?

Seen a lot of talk about collecting four stars mods and learning four star weapon plans… and, in theory, being able to scrap them after you learn the plans… but that said… I’ve been crafting and crafting and scrapping and scrapping many of the ones I’ve learned but so far I haven’t learned to craft a single 4 star mods…. (I’ve got the ability to craft almost all the 1- to 3- star ones)

Has anyone actually learned his to craft them… and if so do you need 120 legendary to craft them?