LOL... A good idea, but I think impractical. I vaguely remember this being asked in the past. IIRC, the universal reply was that it would be impossible for a place like that to exist... for the reasons roger says, plus the fact that the tools would "get lost", or otherwise never make it back to the shop. In addition to the rental fee, you'd have to charge a cash deposit at least equal to the cost of the tool.