Use the head and some of the neck of the displacer serpent on a spider of Lolth's body. Repaint to the color of your choice. Ding! Instant basic neogi.
For more accuracy and detail:
take it off of its base and glue it on the back of an Umberhulk. Paint "tattoos" on the Umber hulk (neogi mark their favored slaves, if you ever read the Spelljammer novel series).
If you are feeling really creative, use some cloth and/or modeling clay to make gaudy jewelry, possibly a cloak on the neogi, and a little cushioned "saddle" for it while it rides on its Umber Hulk slave.
For a neogi hive mother (er, whatever the bloated pregnant one is. I forget the name ATM) glue the displacer serpent's head on a giant spider mini.