Open Hardware scanning laser rangefinder.
It is really cheap - its components cost less than $30.
See "TotalBOM" with price calculations.
Now I'm updating the documentation for this LIDAR.
Some of it I'm writing to the project wiki: https://github.com/iliasam/OpenSimpleLidar/wiki
Please take the simple survey about assembling instructions
Example of Hector SLAM working with this Lidar:
This Lidar is using triangulation method for measuring distance to objects. It can be shown by this picture:
Some modeled pictures of the assembled Lidar can be found here: https://github.com/iliasam/OpenSimpleLidar/tree/master/Misc/Pictures/
Some more info: https://hackaday.io/project/20628-opensimplelidar
Video of using OpenSimpleLidar for Autonomous Robot Navigation:
https://www.youtube.com/watch?v=YHt_NTktmlA
See also my another Lidar project: https://github.com/iliasam/OpenLIDAR