Welcome to the board from Southern California.
Some Chenille fabric, some Minke, a washable velvet, maybe some lace over cotton. Cordoury fabric with different size wales, a scrap of denim jeans with the pocket on it. Maybe some ric rac type stuff sewn on cotton. Something glittery that you can feel the glitter. Most of these would have to be stabilized because if the stretching.
Would this be used a lot and washed over and over? That would make a difference cause then everything would have to be washable.
Use the brightest stuff you can find so he can see it.
I'm sure there are more ideas out there that someone can give you