I've never used a blower with drift cutters on them.
I've been thinking of making some from flat steel bar.
You're first two lines are exactly what I went through last year. Easy enough project, fabrication and paint in less than an hour. But then I picked up a piece of flat stock I had laying in "the pile" and realized how easily it bent and stayed bent. I thought of going thicker but too thick won't slice. Deeper into the pile I found an old lawnmower blade, sharpened too often to be of any use, that I had saved for the steel. Looks like with a little grinding it would do a great job, but I only had one so I still haven't done it.
So I really can't answer your questions except to say make sure the stock you use isn't too flexible, unless it's spring-hardened. I'm pretty sure all the flat stock you buy at HD or a regular hardware store will be fully annealed and just might get kinked after fighting the EOD a few times.
Who the hell let all the morning people run things?