As mentioned, unarmed HAZMAT would be something new. If they are going to be a group of armed (even down to the multiple assault rifles, shotgun and flamer) then I would advise against it. There's just too many options out there already. The better idea would be to sculpt something that is not already available in bulk.
Again, if you're just doing it for yourself or the fun of sculpting, and don't care about making a buck at it, then sculpt whatever you like.