I did this just yesterday. There are lots of ways to do it in natural gameplay, but if it’s just a quick farming session for Palin, to ease the grind you can get them from a crashed ship site. You need a ship with an SRV. They are engineering materials, not cargo, so you don’t need cargo space.
Go to the Cornsar system, there’s a “crashed ship” site (a t-10, not a thargoid ship) on the first planet iirc. There’s a “crashed ship” signal on the planet’s surface. Land there, get in your SRV, find the Thargoid Sensor, shoot the thargoid sensor (takes a little while, maybe 20 rounds?), it will be destroyed and will break into 1 or 2 “sensor fragment” materials. Scoop the sensor fragments. Relog (from the srv, near the thargoid sensor location).
It’s very important not to scoop the Thargoid Sensor itself, because it will melt your SRV, and your ship if you transfer it there. You need to shoot the sensor, and scoop the sensor fragments.
1 or 2 fragments will drop each relog, when you shoot the sensor; each is worth 3 materials, so you can get 25 in maybe 5 relogs, maybe 10 minutes? You will take a small amount of mild caustic damage in the srv from just being near the thargoid sensor (maybe 15% SRV hull total?).
I’d recommend doing this in solo, and getting 50 fragments - not just 25 - so that you can unlock Chloe Sedesi as well, eventually giving you another pinned blueprint.
