One simple tool that is constantly needed

It's Saturday evening when I sit at my summer cottage which is equipped with all comforts of a modern home; running (municipal) water, electric grid connection, fast (wireless) internet (although I could have 100/100 fiber installed here if I wanted (30km from nearest town and 100km from nearest city!) but it just isn't worth it for now.)  Isn't modern living just wonderful?

Yet there is one simple(ish) tool I seem to miss every time I come here but never remember to bring: A simple multimeter. Like with any older house there is always something that needs fixing here. Leaking pipe fitting or roof, failed electrical connection at outside buildings, fire alarm battery and whatnot. For most mechanical and wooden things I have tools (nothing fancy, just enough to do basic repairs), but every time I happen to need a multimeter I remember - again - that once again I forgot or dismissed the idea of getting one there.

Maybe one of these days I manage to get one here permanently. After all, cheapest usable ones cost just few tens of euros (the very cheapest ones have essentially no protections and could kill you - I don't touch them and suggest that you don't either). Not a very big investment for a tool I find myself needing again and again.