Use 1-3 to change shape, Q & W to change hue, press E & R to adjust brightness and use A & S to change size. Click to choose where you want the bottom of your shape to be by moving your cursor to it and clicking
js3D (or Jonno's Scratch 3D engine) is a tool made to create 3D scenes. Unfortunately, there isn't a way to save, but on PC you can right-click and save image to save it that way.