What is safe to stick forage to cardboard?

[Emx93]

We've been using flour and water to stick seeds to cardboard pumpkins for Teddy the hamster and the kiddos were wanting to make something similar for piggies (with forage not seeds obviously) but from what I can tell flour and water isn't safe for piggies- is there a safe alternative?
Thankyou

 

[Ash_owns_guineapigs]

Maybe try making holes in the cardboard and putting forage in it