I like JMP's jigsaw generator, but I had issues with it. It was generating broken puzzle pieces. So I decided to create my own, using my Bezier library:
https://www.thingiverse.com/thing:2170645

I have tested it with the face of Mars, with a 7x7 puzzle. It works quite well:
https://www.thingiverse.com/thing:2671430
(See photo)

Unfortunately, the licence of that thing doesn't allow me to publish derivatives.

[2020-04-06] The Customizer in Thingiverse is still using the very old 2015 version of OpenSCAD, which has many flaws. I had to fix the generation of random numbers because 2015 round the seed number to the nearest integer.