Shapeways once offered a similar process as a trial material called "White Glaze
". The only example I can find of puzzle parts smoothed using this process is in this post
comparing different 3d printing processes. While it probably won't work for SLS, it's interesting to see that this is easy to set up for Reprap owners, but getting detailed enough results for puzzles will surely be a challenge.
Only on this forum would people use a V-cube 7 as a size comparison for a cat
My Shapeways shop