In my Silicone/Eurethane Mold Making Class (MFG 205) we made a rubber mold of a pig.
You can see here in the picture, we are now filling that rubber mold with styrofoam.
As you can see, in this picture, the styrofoam we used is the expanding kind.
According to the manufacturer, it exapnds at a ten to one (10:1) ratio.
In my Solidworks 3D (MFG 204) class our latest assigment was to design a business card holder. I went with the the classic design, assembled from 2 parts, to allow for double and triple card holders, if desired.
Also, as part of the assigment, I added my initials on the backs of the card holders. I fashioned them from raised and filleted geometric shapes.