A friend called, and we started chatting about our lessons. She said she was working on something with her FH, and wanted to know if I could practice. I wasn't available, but I suggested that she take her hopper to the court and do some drop feeding to practice her FH. She said she didn't own a hopper but had a bag of old balls. I was surprised. I thought everyone owned a hopper. I mean, how can you do any meaningful serve practice without a hopper? So. What training aids/practice tools do you personally own?