Avengers: Endgame marked the last time the late Stan Lee would appear in a live-action film with one of his legendary cameos. As his Endgame cameo took place in 1970s, Lee was de-aged some 45 years so that he would appear as a younger version of himself. The vendor tasked with de-aging Stan's cameo was none other than Lola VFX, the one firm that's perfected the de-aging process for Marvel Studios. We spoke with Lola's Trent Claus earlier this week and talked all things Endgame, including the firm's de-aging process 22 movies later.

"There was some work, very minor de-aging done on Captain Marvel," Claus said about Lee's cameo in the prequel. "But that was 10 years ago or something, so not really a noticeable change overall, especially for a man of his age. But for this one, we had to go back 45 years, so it was a pretty sizable amount."

When asked to break down the process behind such a big de-aging, Claus compared it to a work of art. In the de-aging corner of the world of visual effects, there's no set procedure on how to best accomplish the task at hand. Claus makes sure to mention that each shot is different.

"The work that we do, we don't create a CG replication of the actor. We use the actor that's actually there on screen, so we were actually modifying the actor in the performance that was there on set as opposed to re-creating something new," Claus explains. "So, we have to treat each and every frame like a painting, where you're working with light and shadow, and form, and composition, and things like that to accomplish the goal."

"We've got a highly trained roster of artists here that work for us that have been doing this for a long time. Lola started de-aging way back on X-Men 3, and have been doing it ever since. I started with the first, as far as de-aging and stuff goes, with the first Captain America."

To start the process off on the right foot, Claus and his team gathered up as many reference shots as they could, meaning they hunted down picture after picture of Lee in the 1970s. Then from there, they used their proprietary software to make the magic happen.

"In addition to that," he continues. "You have to rely on the artist's knowledge of anatomy, the changes that happen to humans over time, the physiological changes in the skin and the muscles, and the mechanics of the expressions that you make in your face, and also the body, the posture and the build of the body changes over time. All those things have to be taken into consideration."

What's your favorite cameo of Stan's? Let us know your thoughts in the comments below!

Avengers: Endgame is now in theaters.