Agree with Andrew Stewart, JB Weld will fill the hole but do nothing for structural integrity. You should be aware that absent a
backer of some sort behind the hole the JB Weld will require 3-5x as much volume behind the opening as in the opening. JB Weld
is functionally an epoxy like semi-solid with fillers that hardens into a solid and can be plastically shaped. If the opening is into the
bottom bracket area you will have to deal with the glop that ends up there and keep it out of any threads.
Thanks Andy and sch. Nessism is going to upload the pictures for me, so hopefully that will give a bit more clarity on the issue.