Adding points to a point cloud
A good free tool for editing meshes would be Blender. Linux, Windows, Mac are supported. It has a serious learning curve, and is somewhat counter-intuitive in use (right click object to select) unless you customize it.

Plenty of online video tutorials to learn the basics, though, and if you have a membership for Lynda.com, those videos are the best (opinion).

I've used it to pull edges and vertices together, to chop out pieces that weren't supposed to be there, etc. The flexibility and power of the program is amazing, considering the price.

Many artists use the program for creating 3D animations and full length movies. Amazing talent, well beyond my capabilities, but it shows what the software can do.

The website also has links to tutorials and the manual, which is also a work of art.



If you can devote the time to learn the program, anything 3D modeling related will be within reach.