That reminds me. I must check my puncture outfits. I try to keep a kit with an unopened tube of glue on whatever bike I'm using but I end up with plenty of spare patches and one useable tube of glue. Unless you're very lucky once opened, a tube is likely to have evaporated by the time you use it next. When you have more than one bike, sooner or later the unopened tube will be on the bike you're not riding!
I've seen suggestions that you uncrimp the sealed end rather than take the cap off, then re crimp it afterwards. I think the unopened tube option is still the safest. You can buy packs of mini tubes on
ebay -open then discard. That seems a feasible solution, if you'll excuse the pun, though I've not tried it yet. Fortunately, in these days of puncture resistant tyres, I've so far only found myself with a tube of fumes when I've gone to fix a flat in the garage.
As for self stick patches, I did experiment rather unsuccessfully some years ago and came to the conclusion that if I was going to take a tyre off, I might as well do a proper job and stick a traditional patch on or fit a spare inner tube if there was any doubt about the permanence of the self stick option. Maybe modern ones are more effective. Perhaps I should try them again, and do away with the worry about evaporating glue.