If slides take your 12 slides and do a File SaveAs and create .PNG images of
all 12 slides. Create another PPT project with 4 blank slides. Insert
Picture the 1st 4 slide .PNG images into the 1st slide and resize them so
each will fit one quarter of the slide. Do the next 4 images, etc. until
all 4 slides are finished. Save often your new presentation.
If you want to do this with printed handouts, you'll find in the print
dialog an option to print handouts instead of slides. And for the handouts
you can choose how many slides are printed on a paper page (1, 2, 4 or even
6).