Fillet gauge

[Planet X]

There are various versions of this contraption around, but this one was the cheapest my welding supplier had. Basically it is a bit of sheet-metal with the corners nibbed off. You would use this tool or some other contraption to 'inspect' your welds for correct size.
E.g. 1/4 fillet really is a 1/4 fillet . This 'inspection' tool is for me a training aide-mostly a timing thing.

[Blacksmith]

Looks better than the one they let me use in welding school. I ned to get one of those - and about a million other things. No use practicing if you're practicing the wrong (size bead) things!