3D Printing Question

3D printing is really slow.  So slow, that the machine is left unattended to continue the print, overnight in many instances.  The print head is set at 205ºc and the table at 60ºc, and it does bother me that this hot machine is left unattended, unwatched.  I do not know if any fires have resulted, but fires are of some concern, particularly here in Oz.

A substantial component of the printing time is the hidden, internal structure of the object being printed, the “infill”.

IMG_8509 2

In this photo I set the infill at only 3%, but to compensate for that I increased the wall thickness.  The result was a nicely rigid article, but it was a 24 hour print.

My question.   At this point in the print job could I have paused the printing, and filled the cavities with a substance which set hard.  It would have to be done carefully of course, and keeping the level below the printing edge.  It would also have to be cool or cold, so the PLA did not melt or distort.  It would also need to be able to be poured, or injected.  Plaster of Paris comes to mind.  Car filler bog would be too viscous.

Any suggestions?