Just a simple cube folded out of a single square sheet of paper. This model is also called waterbomb.
You have to start with a Waterbomb Base.
2. Repeat step 1 on the other side.
4. Repeat step 3 on the other side.
6. Precrease and then tuck the little triangles inside the pockets. Repeat on the other side.
7. Precrease. Then bring the cube into form by pushing down the top and bottom points, pulling the flaps a little bit apart and blowing air into the hole at the bottom.
8. The finished cube.