Wouldn't it be easier if you just really get a lantern and make some modification to it? If you can't find a lantern, you could scratchbuild it. From the looks of it, in the middle is a ball. Put some end caps and you are done. If you cannot find any end caps, get some thick styrene sheets.
The trick is be resourceful. IMO, pepping this doesn't make sense. Once pepped, you need to find a way to hardent it.