In our basement I have a big box of empty boxes, yogurt pots, Pringles cans etc. I decided the Pringles cans were ideal for making stands to display his Lego models. Some of them I left full size and some I cut down to give a variety of heights. These then got covered with construction paper. You could use any paper or even paint them what ever you fancy. The lids were then put back on to give a good display platform.
The models then got rearranged using the new Lego display towers. Room for even more models.
Very simple but very useful.