Help Me O Plc Gurus Of Wisdom

Hi Guys I Think This Would Be a Good Place To Get Some Info.
I Am A Final Year Student In Ireland Studying Control And Automation
Engineering,

For My Final Year Project (Quite A Substantial Percentage Of My Degree)
I Have To Make A Demo Piece With A Plc.

Basically Its Going To Be A System That Pushes A Plc To Its Limits, I
Have A Big Bucket Of Parts At My Disposal That Was Salvaged From An Old
IBM Disc Platter Machine. Everything From Pneumatics To Hydraulics And
More Servos And Stepper Motors Than You Could Shake A Stick At. (Irish
Expression That Means ALOT).

The System Is Going To Be Used As An Educational Tool For Up And Coming
Control Engineers As Well As An Exhibit Piece For The University Open
Days.

I Was Thinking Of Doing A Kind Of "Mousetrap" (If You Know The Board
Game) Type Of Thing With A Ping Pong Ball Moving Around Various Levels
Of A Course With Sensors, Actuators And Pneumatics Moving It And Even
Levatating It At Points. Basically I Want To Get Almost A Domino Effect
With A Ball Completing the Course And Being Reset, Using Conveyors,
Motors Kickers And Anything Else I Can Get My Hands On.

Im Having A Bit Of Trouble With Ideas And This Is Where I Consult The
Plc Gurus (you).

The Rig Should Be Educational, Spectacular To Look At And Fun For The
Open Day.

Does Anybody Know Of Any Existing Similar Setups? Or Anywhere Online I
Could See Some Photos Of Them.

Failing That Any Ideas Would Be Greatly Appriciated,

Thanks For Your Time.