My SIL (S = son, not sister) is a professional mechanic who works at a Porsche dealer.
His dealership provides a uniform via a laundry service as well as specialized tools. But he has to provide some supplies. Here are a few things that he really appreciates.
1) A big lunch box and an insulated water bottle
2) Terrific socks
3) Steel toed boots
4) Rolling tool box (Harbor Freight)
5) An LED, battery-operated light bar to take under a car
6) A mechanic's creeper
7) A first aid kit with some Motrin and Bandaids
8) A few really good tools. Bonus if you can have them engraved with his last name. Quality > quantity as some cheap tools break quickly or are just a bit off when accuracy is important
9) Some great undershirts. My SIL was wearing the typical white V neck cotton undershirts but in certain positions, they'd really chafe. He ordered a 5-pack (more or less) from Amazon of thin, shiny,
"high tech" synthetic tee shirts in dark colors (dark gray, navy, black, forest green). They were not marketed as undershirts; they are actually just normal tee shirts. I wish I had a link. He said they are much more comfortable than cotton undershirts. BUT they hold BO quite a bit so they use some strong laundry detergent in their top loader...
Could you secretly contact the program he is graduating from or his new employer to get some ideas?