I've used the same idea that paramedicpete has with the safety can openers. After opening the can and enjoying all the meaty or soupy goodness, I just fill it with whatever survival stuff I want and use a small bead of JB Weld around the rim to reseal. It works great if you are using cans with pull top lids. Spam and Campbell's pull top soup cans are the only ones I have tried, but they seem to work well.

No affiliation to Spam, Campbell's or JB Weld. I just like to eat and stick things together.