It's a 3/16" steel rod with a scraper welded on the end:
I ground the 1/8"thick piece of tool steel roughly to shape, and when it was still red hot from welding it on the rod, I quenched it in some water. I'm not particularly concerned with exactly how hard it turned out, because I can easily sharpen it each time I use it.
Mounted in a handle, the scraper is long enough to reach where I need it to go:
I simply bend the rod to adjust the scraper to the best angle, and with a few controlled strokes, I have the excess glue cleaned right off:
See? It looks pretty much the same as the untreated side:
This tight crack needs no internal reinforcement.