Hiya,
  For my rotating design... which I havnt yet finished... I designed a part that acts as a hand rest as well as a corner hide'r.
  How so?  I used 2 long thin pieces of wood and glued a thin long piece of foam to it with hot glue.  The wood pieces were about 2 inches appart i think.   Then, covered the whole thing with a fake leather material i got from a fabric store.  
  You have a few choices now.   My first idea I pre-drilled holes into the control panel edges, and matching holes into the wood strips (before assemblying them)... I would then use string to tie the strips to the panels.
  However... ive though about it more... and think maybe industrial velcro may be a better route.
  The pad then sits on the bottom/ top of each control panel... and while covering the space between... it also makes a nice wrist rest. : )
  My panel is completely uncoverd however... so for covered designs that foam may get in the way.  Then intead... just use a heavy fabrick, flexible plastic, film or something simular that is flat and durable.