Easy for toddlers to break doors off (and/or get hold of and tip the whole comptuer over) so any doors must have locks, if OP's problem is understood accurately, and the bezel has to be attached solidly to the case so the whole thing can't easily be pulled off. I would suggest looking at some of the less expensive CoolerMaster cases too as they do have steel chassis often with aluminum fronts - but I have no idea what method us used to attach the bezels to the frames. Some of the doorless Antecs may also be options.
.bh.