I almost spit out my coffee when the OP stated "for free", as if not having to pay anything but time, my most valuable asset, was some perk.

I'm sure the OP means well, and it may have been a success for them, but I don't know anyone in my circle who would participate in something like this, unless they were utterly desperate for a job. I thought there was a serious talent crunch? Who is courting whom?

I wonder what sort of engineers self-select in a process like this?