*temporarily removes duct tape to address Ray*
The thing about cardboard (or the foam board) is that yes, it can be a fragile medium, depending how it is applied. I've found that how it's applied (i.e. the understructure) can make an immense difference. The foam board skeleton of my command module, built at right angles, skinned with styrene, can in fact be immensely durable. Even my side pods are like lightweight bricks!
I haven't seen that Enterprise you speak of, but it does sound like a tragedy waiting to happen, though. The Eagle is one thing, but I can't fathom how the builder can make, and have any confidence in, those nacelle pylons or saucer 'connector'. :confused