I used slip to join the edges and make them look neat, and also put reinforcements on the inside of the cube to strengthen it.
I next rolled out some more clay and made cylinders, to put together to make a repeating pattern similar to how I made the triangle.
I put marbles into the bottom of the cylinders, to hopefully melt and create a decorative abstract piece in the bottom of each cylinder. I have used marbles because I have lots of marbles and would like to make something new out of them.