You'll need to have completed
first before you can get this achievement.
After returning to The Outpost/Ark with Koichi, you'll notice a new shop has appeared just to the left of The Ark teleporter, Treasured Trophies. You'll be able to trade for the Perfectly Generic Item there. You'll need to trade one of each of Scorched Core, Cryonic Extract, Venom Sample, and a Static Cell. These can drop from specific enemy types, but there's an easier way to get them. You can buy the four elemental Fluffalo eggs from the Terramart in The Outpost, which like Mooshi and Hens who drops milk and eggs, these Fluffalo will drop these four elemental items over time over and over.
Trade for the Perfectly Generic Item and this will pop.