Craft a Projector and right-click with the items you want it to display. The side you click on and the direction you’re facing will determine the way the itemstack is displayed. In Minecraft 1.9 you can only interact with a Projector with your main hand.
A basic Projector can only display one stack whereas an advanced Projector can display one stack per side.
Upgrading a Projector
To get an advanced Projector simply add four Gold Ingots to it. In 1.7.10 the recipe is not shapeless; check NEI.
To camouflage a Projector add the block of your choice. Any solid block will work. (To be exact: If block.isOpaqueCube() evaluates to true, then the block will work)
You can use Holographic Victory Monument in your modpack, but monetization (apart from Curse rewards program) is not allowed.