I used a solid styrofoam block, hollowed it out in the middle and cut the hole for the door. I then used sanded floor grout, took about 5 layers, starting out with a thin mixture and working to a pancake batter thickness for the last coat. You have to let each layer dry 100% or it will not work. During the last coat I dribbled some over the hide for the effect. I then painted the hide inside and out with a semi-gloss latex paint I custom mixed @Lowes for the clay/brown color. Make sure to only use a latex paint, its non-toxic and is safe for your little buddy. You dont have to paint it but I like using the semi gloss paint for ease of cleaning and it keeps the grout from being dusty over time. Plus you dont have to use a toxic grout sealer.