I wasn't curious about the actual size of the Droids.
I've seen this film a dozen times.
One of the best SciFi films ever made.
And I am familiar with the disabled actors who played the Droids.
I was just thinking it might be fun to build a full size one.
1971 - "Silent Running" Drones - Doug Trumbull, Don Trumbull, Paul Kraus & James Dow (American) - cyberneticzoo.com
However, Uhu's file is not readily editable
and the model would require some serious structural modifications.
Dolza's try at doubling the scale model might be the maximum the design can handle.