How can I make a tri-fold table that folds flat on itself without using card table hinges?

Card table hinges look like the way to go, but they are hard to find and are expensive. I don't want the hinges to get in the way of game play on the board and it must fold up, not down.How can I make a tri-fold table that folds flat on itself without using card table hinges?
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a bit hard to read the drawingsHow can I make a tri-fold table that folds flat on itself without using card table hinges?
piano hinges work great