Here's how I did it:
I used 4 used up toilet paper rolls, 4 plastic cups, 1 plastic fruit container and lots and lots of paper towels.
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To put all the ingredients together to build the shape of my castle I used painter's tape, because it's mostly paper. Then to put the little pieces of paper towel onto the shape I mixed a bowl of wallpaper paste. I put about four layers of paper to shape it up just fine.
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I let it dry for about a day or two. And then I coloured it, castle colours! Using an edding for the details and finishing it up with gold and silver paint.
Just a silly little side project :)