Second layout and clamp stuffs. Scribes, center punches etc.Can't have enough.
I definitely Third this! I love me some Starret automatic center punches
Personally, I'd probably just ask him what he could really use, or what would really make his job easier/safer/funner/whatever. Rather than trying to guess.
What type of welding does he do? If he TIG welds, a luxury item would be a quality tungsten grinder. Most hobbyists won't shell out for good one, but I'd love to have one! I settled for a small cheap bench grinder cut in 1/2 (only 1 wheel instead of 2), mounted to my welding cart.
One thing I've been enjoying lately is the large strong hand magnets that have an on/off switch. The largest one really does work really good!
I'm not a welder, I'm a hobbyist who migs and tigs for garage and vehicle projects, so I don't know what type of tools he can (or can't?) use on the job, but pretty much anything from StrongHand seems to be nice for hobby garage use!