Photo Three; Blue Foam. Used in the building industry and comes in a variety of different thickness. This particular image shows 20mm, 30mm and 8mm thickness.
Photo Four; Green Foam. This is a new product to me and the one that prompted this short article being given to me this week. It is much finer than Blue Foam is slightly firmer and has a powdery texture.
Photo Five; Soft Resin. Not really apparent from the photo, but this is more like soft resin, than foam. I have no idea what it is supposed to be used for but it can be cut, carved and sanded easily - it does not take pressed detail as well as blue foam.
Photo Six; Soft Resin 2. This is a brittle resin slab, sorry cannot find a name for it. I have used it to make individual stones or bricks, can be sanded and is much firmer than foam.
Photo Seven; Balsa Foam. I was given this block by a technical teacher from a local school. It is used for student projects and is available for artists and technical artists to build props. I use it very sparingly as it is the only block I have.
Photo Eight; Hard Resin blocks. I have a few, they are very heavy and much more difficult to cut, needing a hacksaw. It can be sanded, but must be dangerous as there will be dust.