It's no sweat for me... only one family member is bike savvy (my brother in law who lives next door), and often he'll borrow a tool without asking and I won't even know until he told me he did! (Because he takes it, uses it, and puts it back exactly where he found it!!!!!!!!!!!). So that ones no problem, I only have 2 local friends competent to work on their own bikes... and in order for them to "borrow" a tool, they have to come over... and it's enough distance that usually they simply drive and bring their bikes... they ask for a tool, I dig it up, they use it, or I show them how to use it, and they give it back. Anyone else who happens to touch my tools, it's 99% of the time while being taught to do a process on a bike... that's when most of the time they don't get handed back to me or sorted, but I keep a bench by the process for that stuff and tell them just to lay anything on it and let me clean up at the end, rather then risk them screwing up my organization or lack there of.