I finally found a way to make 3D printable puzzles which I’m satisfied with, so I decided to share the procedure in case someone is interested. It’s my first “tutorial”, and I’m a newbie in most of the tools I used, so there’s probably a lot of room for improvement.
Continuing my project of printing puzzle maps of all countries on Earth, this time I printed Central America. I chose it for having few pieces, so I could quickly test the new method I came up with. I plan using this method to also print all other landmasses on Earth!
Without further adieu, here’s the tutorial:
[Update: The brush tool’s width seems to vary according to how far you’re zoomed in, so what I do now is adjusting its width according to the width of the pen (which is adjustable in mm). About 0,7mm works well for me. Then you just have to trace the whole picture under the same zoom. Tracing with the pen directly does not result in a smooth fill later…]
The files for the Central America map puzzle can be found here: http://www.thingiverse.com/thing:11112
Check out all the maps I’ve printed here!
my Shumi 
this is really great! I wish i could do like you did. I would love to see a board that the pieces could fit into (think a map of the world pressed into a board) and then you could put the continent with the individual pieces and then place a full pic of the continent over it. This would be an amazing teaching tool!