I would like to make something out of something and then fine-tune it with chisels, make a head sculpture. Plaster struck me. But if it will be machined then and it will not fall off in large pieces.
If you want to start building from a cube and this is one of your first attempts, try using one Ytong block. It works very well, scratches and goes to cool nicely. At the same time, it is also relatively cheap, with a long service life. When forming from plaster and clay, the opposite procedure is usually chosen. / You gradually add and do not remove material /