Our late dumpster era dining table has a wicked sharp edge on a supporting brace. The kids are almost tall enough to put a dent in their skull when they stand up.

I could file the end of the brace round, but this solution is more fun. The brace cross-section is 52 x 26 mm. It already has one screw about where I wanted to anchor it, so I made 3 mounting holes for good luck. One short #8 or #10 screw will hold it in place.