The acrylic deck of the PPRK fastens securely to the metal hexagonal frame with 6 screws.  This gives the finished kit a solid feel, but also makes it difficult to get at the controller.  When experimenting with the kit, this can be inconvenient.  A simple modification makes it easy to remove and replace the deck. 

The modification requires three 4-40 wing nuts and three 5/8" 4-40 screws.  The steps for this modification are listed below. 

Remove the six screws, washers, and nuts used to mount the deck. 

Take three of the screws removed and mount them back in the frame so that they are pointing up instead of down.  Arrange the screws so that they form a triangle, one screw per frame piece.  Do not attach the acrylic deck with the screws.  The screws will act as pins for aligning the deck. 

Re-use the remaining nuts and washers to mount the 5/8" 4-40 screws in the frame so that they are also pointing up.  The three long screws should also be arranged in a triangle.  It is important to use triangular arrangements of the short and long screws to keep the structure as strong as possible. 

Place the acrylic deck on the six screws.  The nuts securing the six screws will create a gap between the deck and frame that is useful for passing wires between the controller and deck.  The short screws help line up the deck and hold the frame in place.  The long screws provide fastening points for the wing nuts. 

Fasten the three wing nuts to the three long screws.  Do not overtighten.  The wing nuts hold the deck firmly in place. 

New deck fasteners. Red lines point to new screws and wing nuts.

The kit in the photo is the Deluxe BrainStem PPRK , but the modification will work for any PPRK kit.  The robot shown above has a second modification that may come in handy.  Sometimes the foam tape holding the 9V battery clip in place can become weak and detach from the deck.  The 9V battery clip may be secured to the top deck through one of the small existing holes with a 2-56 screw and nut.