Chamfered head washer thingy for M6 bolts

A little washer/spacer thingy that I made.... I thought I ordered button head bolts... but then blister thumb-bolts turned up. rather than going through the pain of trying to get a refund/replacement, I simply made this washer thingy.

The idea is, the bolt is to be mounted on top of a cabinet panel, I didnt want the exposed bolt head to become a bump hazard... hence this thingy (no idea what it's called, i'm sure there's a proper name for it) will create a nice shroud around the exposed bolt