I poke holes in toilet rolls and stuff sultanas in them. My bun rolls and moves the toilet roll around and nibbles out the sultanas as she goes. Be careful not to use too many sultanas as they are a treat. Another toilet roll trick I do is cut them into quarters and put peices of her fresh fruit or veggies in them and hide them in places where she goes. Or even create a trail (Hansel and Gretel style). My bun follows the trail and as she gets to each toilet roll ring she picks it up in her mouth and tosses it to the side revealing her food underneath. I use 1-2 basil leaves in each ring or I slice up a small strawberry and use that. In terms of snacks try freezing some slices or chunks of banana, watermelon, Apple etc... It takes them a bit longer to eat them or they just lick them. Perfect in hot months too!