I only steal the best.
Snapped living hinges is my area of expertise. Ugh. Waiting forever for a living hinge to cut only to snap it, is sad.
Double check the edges of the hinges to make sure they’re cut through. If there are attached bits even if seemingly innocuous, the piece will snap.
I found quickly wetting (not soaking) a stiff hinge will help it to bend the first time.
Keep in mind that hardboard will sort of disintegrate if it gets too wet. Just a quick trip under the tap. I used hot water.
Do not rub the hardboard or it will pill.
Been there, for sure! This design has enough hinge in it that it didn’t have any trouble with the first bends, though. (I’ve only made it from Baltic birch plywood, so YMMV.)
One trick I learned here is that alcohol won’t make the wood swell like water does, so that’s what I use now for wetting my more stubborn living hinges.
Welcome back about. If you want to make hinges more robust then get rid of all the pointy places as sharp corners will be where breaks happen. where there is a curve the laser does not stop and make an irregular hole but a curve keeps the forces from concentrating there If the cut is dumbell shaped and there is a bit of wood dropped out you will not have incomplete cutting. I have seen just circles at the end of a straight cut to almost super long ellipses but they all are less fragile than spindle shapes.