I provide Mr Toffee with stimulation by giving him plenty of things to play with. He has several soft toys, a few small cat toys and some balls. He also has some kids toys, a miniature yellow American foot ball, rubber duck and more. He also - along with many other hogs - likes sticking his head into a toilet roll tube, which is very entertaining to watch! Although not officially not a toy he has a ferret tube and he runs up and down and along it, as well as using it for taking naps in the evenings.
He doesn’t play with his toys very much and you have to change them around a lot to keep him interested, hence the large selection.
Mr Toffee, like most hedgehogs, is very curious and loves to hunt for worms; I often hide them in or around his toys. The most successful is with a cat ball that has holes in, we put a worm inside and he pushes it along poking his tongue in the holes trying to get it.