What's a supernatural creature to do to pass the time on the long, cold nights during winter in New York? Why, craft jewelry and repair textiles of course. The Jinni uses his idle hands to craft a "miniature golden pigeon" (7.11), an owl as an apology to Arbeely for questioning his faith, and other little metal animals.
For her part, the Golem practices taking apart dresses and putting them back together, "uncreating and then creating it again" (8.57), becoming an expert seamstress in the process. Sewing and making jewelry are decidedly human past-times, and they're a way for the Golem and the Jinni to connect with the culture they've found themselves in. And that they do so similarly, represents a connection between the two of them as well.
Despite both crafting for similar reasons, the Jinni is more artistic than he is practical, like the Golem and Arbeely are. When someone comes to Arbeely and asks for a ceiling to be made, the Jinni turns it into a work of art, rendering in the tin a "portrait of a vast desert landscape" (16.95). Arbeely is angry at first (it wasn't what the customer asked for) but he realizes how beautiful it is, and he can't bring himself to destroy it. It's art, and as such, "It was no longer his to destroy" (17.52). Hmm… can't the same thing be said for the Golem? She was made, too.
The Jinni also makes necklaces and jewelry for another customer. His masterpiece is a necklace with discs of blue-green glass. It's a Bedouin wedding necklace, and the idea comes from his subconscious, his years in the desert that he forgot while trapped in the flask. Sophia ends up wearing it for an engagement portrait. Being called a "queen of the desert" (21.71) is a reminder of her brief love affair with the Jinni, an affair that left her alone and miscarrying his half-Jinni baby. So while the necklace may be beautiful, it is also tinged with tragedy.