Finally something to do with your your extra Fortress set... Make your own dice tower!
Uses only a single FotA. Requires no glue, no paint, no knives or scissors, nothing other than the pieces that come in the box. Assembles just like any other castle set-up. Even the two angled ramps (the top hopper and the bottom deflector ramp) use no special equipment, struts, or glue to hold them in place. They just prop up snugly and securely on other parts of the set.
This is version 2, which features an awesomely improved exit/deflector ramp developed by ScrewDriver. It solves the two issues which plagued the first version: dice occasionally got caught behind the door hinge; and over time the deflector ramp would come apart. No longer.
For full discussion, or to download the build instructions, please see this thread.