Chariot-style double ride-on floor sander.
Fullsize image: https://s3-us-west-1.amazonaws.com/h...r_fullsize.jpg
https://s3-us-west-1.amazonaws.com/h...elt_sander.jpg
Previously:
https://www.homemadetools.net/forum/...309#post121825
https://www.homemadetools.net/forum/...2506#post76487
https://www.homemadetools.net/forum/...545#post122996