I have a DIY cage made of wood. It has three levels and wire on the front and i'm concidering stapling wire to the walls as well. What i'm worried about however is how i'm going to attach things like those rope toys and ledges made for birds as they have pretty large ends that i'm worried about fitting in the inside wire. Im nervous about using nails or screws because I dont want to risk them getting hurt. I was concidering those little stick on hooks used for paintings and stuff lke that but idk how durable they would be and I don't want the rats to pull it down and chew on the adhesive.