Take the borrowed tool back with a thank you present.
I have "lost" two fishing books loaned to a work colleague who left while I was on holiday. GRRRR.
Dave...I still have a Colourtune tucked away in a drawer in the garage. Unopened for many years. I also nearly bought an SPQR tappet adjuster too but held off.
When playing rugby one of the team was always borrowing kit to play. In the end we all refused on the match day and he had to drop out. We had tipped off a replacement who stepped in. He was not picked again until he bought his own kit( boots,shorts,socks).