Tips on how to "sand" off part of a 3d object / increase spacing in a jigsaw puzzle

Hi

I've been trying to figure out this challenge for a while but I've gotten no closer to a solution.

The simplest example of what I'm trying to achieve is to imagine 3D printing a jigsaw puzzle. In order for the pieces to have more spacing/margin I would like to sand off a small amount of the outside of the puzzle pieces. Does anyone have an advice on a program or technique that could do this?

A little background info. I'm actually trying to 3D print a map of a country with some spacing between the main areas/counties. My first thought was to just resize each piece individually but of course this wouldn't help at all. My second idea was to look into techniques for hollowing 3D models before printing. That would potentially give an idea on how to solve this. Sadly, most of those are either using a one button hollow functionality or are simply using basic objects (sphere, cylinder) to hollow the object. So I'm still no closer to solving this.

Thanks for any idea and tips on how to get closer to what I want to achieve here...

/BladeR

If you are creating the map using the method of extruding a polyline drawing, you can use an offset feature to reduce the outside by the desired amount. I'm barely literate in Adobe Illustrator, but can recommend Inkscape to perform the offset task. Fine details along the edges will be lost, but you wouldn't have much in the way of fine details on something 3D printed.

If you are working with existing 3D models, there is also an offset feature in OnShape and Fusion 360, but you're on your own with those. I suspect they work in the same manner as Inkscape, though. Of the two, OnShape will be the easier to learn that specific feature, as it is more user friendly, in my opinion.

Please reply with additional information regarding your source material.

both flashprint and simplify3d have settings to reduce or increase the gaps between surfaces.
so essentially 'sanding' or 'adding' material.

No idea if cura or any other slicers do this as well.