I would mark them as owned and then put a note in the condition section that it was home-made. After all, I see the collection utility to be primarily for my own use with a secondary benefit of providing information to the community.
“Questions are a burden to others; answers a prison for oneself.”
I mark any game that I have the components for, and an interest in playing, as owned. I use the collection utility to track what I have at my disposal, not as a formal census of "real" copies of games in the universe.