Earlier this year, LEGO woke up from its swingin’ ’60s Don Draper haze and realized that women scientists exist and — hey! — maybe it would be a good idea to reflect that reality in its vast line of minifigs. The resulting set — featuring an astronomer, a paleontologist, and a chemist, all female — went on sale recently and sold out quickly, never to return. But some say LEGO should consider bringing on these female scientists for a full-time gig.

The idea for the LEGO Research Institute came from Ellen Kooijman, a female geochemist and LEGO fan whose proposal on the LEGO Ideas platform quickly garnered the 10,000 votes needed for consideration. Then the sets went on sale and sold like hotcakes, both because of the appeal and because some people just love LEGO.

But because the Research Institute was a fan-created set, it was only available for a limited time, and a rep for the company confirmed to the NY Times last week that there are no plans to resurrect it.

In the hopes of changing LEGO’s mind, more than 1,500 people have already signed a petition asking the company to bring back these female scientist minifigs and make them permanent.

“A large section of LEGO’s customer base is female,” reads the petition, “an even larger section have used their voices and wallets consistently for three years to communicate they are wanting, ready for, and will purchase sets like the sold out LEGO Ideas Research Institute… With proven market demand why would LEGO not make more of these?”

In her review of the minifigs, Kooijman had a number of nice things to say about the final product, but did offer a couple of criticisms from a real scientist.

“I strongly discourage wearing make-up in the lab, because it may cause contamination of the samples,” she writes. “I’m surprised they didn’t give her protective gloves though, like the previously released scientist figure had. In my personal version I will definitely change that, because safety comes first!”