I recently picked up two Pelican cases really cheap. The only catch was that the prior user had cut a 1" hole in the side of each. They were using them to store batteries, so they had a sealed connection coming out of the side.

I've removed the connection, so now I just have a clean 1" hole. Any ideas for the best way to patch/repair this?

I reached out to Pelican, thinking that if I could get some more material, then I could plastic weld a plug in place. They couldn't provide me with anything, so I am open to suggestions.