While I work in IT these days, I still do and have been and electrical engineer. Safety is obviously the key here, I would certainly not be willing to put that in my kids room for example without taking the proper precautions. Plastic sheeting is not a proper precaution. You can buy cheap cases from fleabay that would do the trick, or buy a sheet of 3mm Perspex and manufacture a case using hot glue and a dremmel to cur the holes as required. To fix the PCB to the Perspex use standoffs as already mentioned, which also cost pennies.
In many countries, insurance policies will not pay out if there is an incident with modified devices unless you have them certified by a qualified engineer. In most cases this does not cost much, but it is something to think about.