Here’s a sensory box I used in my preschool classroom over the years (with kids spanning 3-5 years old). It’s super easy to make with a small shoebox sized plastic container and a generous helping of hay.
I added some little people farm animals (and sometimes swapped these out with some wooden farm animals I had), some cotton we acquired on a trip to the Pumpkin Patch which also had a cotton field (cotton balls would work if you don’t have true cotton), a real duck feather, and a packet of bean seeds (fun to shake!)
My son is 7 and he still enjoys things like this. With older kids or under close supervision you can actually include seeds not in the packet. In my preschool classroom I couldn’t have any chocking hazards. We handled real seeds but in a group circle setting and not in center free play time.
My favorite thing to do with this box is to not only get it out in the spring when we were learning about farms but to get it out around Christmas! In the box of hay at Christmas time I would put child friendly nativity figures, small strips of cloth, and animals we commonly associate with the nativity scene.