I've a home made 2" GHT boring head but mislaid the cutters. It was quite simple to substitute a slot drill using one lip.
Some time back, I recall that some one writing in Model Engineer used a broken twist drill as a lathe tool. One of my old associates once demonstrated how he used motor cycle spokes as miniature boring tools. He went on to show how he ground up Allen keys for the same purpose.
In his various books, GHT describes how broken centre drills are used to make boring tool bits, internal threading tools and parting tools.
I've been known to use cracked ball race cages- which are nice steel.
Nothing new, is there?
Norman