"Wait, let me try that again. Can you stand by a window this time?"
Luckily for movie history, the suit was tailor-made for Weller, and since they didn't have time or money to make a new one, the producers had no choice to hire him back. Yes, like everything in life, Hollywood too is governed by a heady mix of fear, pragmatism, and laziness.
The Original Alien Suit Had An Actual Human Skull In It
When he wasn't busy hawking stereo equipment or riding around on his backyard toy train powered by nightmares, Swiss artist H.R. Giger was changing pop culture. Most famously, Giger's paintings influenced the look of the Alien movies... and presumably adorn the walls of Hell's dental offices.
20th Century Fox
Have we ever mentioned that this kind of looks like a dong? Just checking.
Giger himself worked on the film as well, personally crafting the sculpture to use as the model for the Xenomorph costume -- and if you think he just popped by a Target to pick up some papier mache and a glue gun, you're out of your goddamned mind. For starters, he used a real human skull for the alien's face, as seen in this video, and felt the need to state that insane fact twice for good measure.
20th Century Fox
"Definitely not a real alien one that I gathered during my intergalactic travels. Nope."
When asked about the skull in an interview, Giger confirmed the story followed by a terse "Don't ask me where I got it" -- which would be a shady thing to say about a pen or a stapler, let alone a piece of the human anatomy. The film's writer, Dan O'Bannon, witnessed the alien's creation firsthand, elaborating that "[Giger] took a human skull and jammed it right on the front, riveted it into place and then started modifying it ... and he takes out his hacksaw and he saws the jawbone off and extends it like six inches. He puts an extension on it, and creates this distorted jawbone." The costume also featured other assorted bones, and bizarrely, condoms were used for the alien's lips, for that sensual touch.