Years ago, I was installing central heating in my house and I found a tin of solder flux under the floor. ...........and I'm still using it.A variation of what davidyat said: An electrician I worked for one summer in high school told me to put everything right in the middle of the room so that it is easily visible. I don't know how many tools and pieces I lost by placing them on top of heating ducts or near furniture in customer's houses "just for a minute because I'll need it next." Years later I was a "facilities" guy and found lots of tools from contractors on top of heating ducts or in other places above drop ceilings. In that later job, I followed the rule from the old electrician and only lost the tools I loaned to people "just for a minute."