My hope was that I could cut a window rather than splitting the thing in half. That way I could use rivets or screws and castle nuts to attach a new sheet of aluminium over the hole rather than welding the thing back up. The benefit of this is that if I needed to repack it again in a year or two it would be much easier.
The drawback is, I think, that extracting the old packing and putting the new stuff in would be more difficult and maybe impractical.
That would be extremely useful if you remember where you saw it. I've had a look but I can't find any information or pictures.