I'm bouncing around the chapters when mapping and I came across, problems. Do you want to use the portal gun in the Time and Gravity Chapter? If you don't, it will be staged underground and Caroline will be in charge. Then I need a voice actor for Caroline, and a world model of a dimension changing device. If you do, I have a harder time to think of a puzzle that uses one and the chapter will be staged in modern Aperture.
Do you want all dimensions in the chapters? An Iron Cube, you cant pick it up until you are in fluffy dimension. This goes either way, it can be underground or Modern Aperture.
Do like this new Portal Gun?
I found out the new portal gun, uses new particles, instead of the combine muzzle.