Slime in the lava lamp containers! It's like $3 at 5 Below. To make it slimier (texture preference depends on the individual), just add a little spring or filtered water. You can also put little styrofoam balls in it to give it more tactile stimulation. You can get it in a variety of colors and also glow in the dark.
Clicks (also known as Twiddles) The satisfying click this toy makes is everything. The way their made is also very textured in a way and can also be worn as a bracelet or necklace if big enough to fit safely over your head.
Tangles These are everything. I wish I'd have had one as a teenager. I want a textured one, but currently have a normal Tangle Jr. and it's honestly the perfect size for on-the-go and at home.
Bubble Motion Tumblers The bubbles. Especially the ones with something inside the tumblers that move when the colored-water falls on it.
Chewable Jewelry from Stimtastic I'm not as much of a chewer as I was as a kid (RIP straws), but when I get the urge, the ones stimtastic sells are awesome.
Squishy Panda by Stimtastic It's just so tactiley and visually satisfying and smells vaguely of either cinnamon or sugar and it's just great. It's like 3 sensory stims at once.
Fidget Cube by Antsy Labs The only good cube I've found is the original one by Antsy Labs. It has a great clicking spin dial, too, which is easily my favorite part.
Finger Spinners They're mini fidget spinners and they're the perfect size for concentration so they won't really distract you. They're also super cheap. Not recommended for children under 8 or anyone who will stick small things in their mouths - choking hazard.
DNA Ball I haven't used one since I was a kid in occupational therapy, but it is awesome. I believe it's essentially a soft plastic ball filled with Orbeez/water-beads. You can make something like them by putting engorged water-beads in a water bottle, putting a clear balloon over the spout of the bottle, and flipping over the bottle and squeezing the beads into the balloon before tying it off. Same goes for sensory brushes - but please have an occupational therapist show you how to properly use them. I've found they are no longer really recommended, but I loved them as a kid.