How did they create the fictional short film "The Shrinking Lover" for this movie?

As in - did Almodovar and co take and reconstruct such scenes from other silent movies or did they SPECIFICALLY create that short film "Amante Menguante" for this movie, obviously based on a classic 50s film "The Incredible Shrinking Man" and add some towards the end especially explicit content?

Anyone know how it was done and achieved, thank you.