Given that [LAS/LAZ][1] is LiDAR point cloud data, there is a GIS tool called [las2tin][2] to convert these files to a triangle based mesh called Triangular irregular networks or TIN by the GIS community. Once you have the mesh, Google should be able to help you find a way to convert the TIN to an STL. You will need to scale down the STL after creation, as the TIN will probably be at 100% scale.

More details for the process that I got from Google are available [here][3]


  [1]: https://www.loc.gov/preservation/digital/formats/fdd/fdd000418.shtml
  [2]: https://www.cs.unc.edu/~isenburg/lastools/download/las2tin_README.txt
  [3]: https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxzZ2NjYXJ0fGd4OjY5ZDk1OTY3MjY4OTY4NWM