We're going to get him a play castle for his birthday, but in the meantime I thought we could have bash at making one using loo rolls.
So to make the towers, I cut out notches all round the top of four loo rolls, and then we folded the leftover bits down to make battlements. Then I made cuts all round the bottom of the loo rolls and we splayed them out for gluing later. I also cut two long slots up two sides of each loo roll.
For the walls I cut up pieces of cardboard box and then fitted them into the loo roll slots. We cut a doorway before gluing the splayed bottoms of the loo roll towers onto a base of stiff card.
We painted the castle (purple, obviously), and then when that was dry we painted the base. We found a rainbow sticker for the crest over the door, and some bits of material to make flags (glued round toothpicks).