I cut that one and it looked ok but its very floppy at the base and too rigid at the top. So I made up another cut where I added more tabs near to the base and cut it too. But this one was too rigid at the base now.

I think I know what the problem is. I was thinking that the amount of length on the laser lines would determine the amount of movement it would show on the card. But I dont think that is the case any more.

In the first cuts I had the tabs at opposing sides of the hill and the card bends at the tabs and the bit between the tabs is an arc which bends up and flexes the model. In the second cut the tabs are around the contour such that the laser lines are mostly straight between them and in this situation the flex needs to stretch the card which we know from the previous experiments that it wont. So I think its really important that its the angle between the tabs that is more important than the length of line between them. I reckon we need about 120 degrees or so minimum between the tabs in order for the part to bend and at 180 its really flexible. The length makes a difference as well but its the angle that makes more difference. A spiral is like having the tabs at 360 degrees so its super flexible to the point of being useless.

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