This is part of my hackaday project at https://hackaday.io/project/11312-3d-prints-for-teachers-of-the-visually-impaired. This openscad script can make prisms, pyramids, cylinders and cones with a specified volume and height. It can be used to show that a prism/cylinder will have the same volume as a pyramid/cylinder with the same base and 3x the height. Update: We got feedback that the tips of the cones/pyramids might be too sharp to handle comfortably, and modified them so that the tip is truncated slightly. To make it even less sharp, there is now an option to add a ball to the end (the top of which will be where the top of the pyramid would be).