Hey, Rob, reckon you could add a picture of your playfield box, ive possibility got 2 playfields in the queue that might warrant a HRP treatment.
Cheers 

I don't have a pic sorry mate, and its already sent. I basically used 3mm ply for top and bottom - cut oversize by 20mm or so, in order to wrap the playfields, and some 16mm mdf for the sides, cut it about 70mm high, then just screwed the bottom to the sides, wrapped the playfields up, put them in the box, then screwed the top down to the sides.