Medical droid designs by Ralph McQuarrie for The Empire Strikes Back (1980).
All the different image sizes make this post look a bit unwieldy; I tried to arrange them in the best possible way. I’ve posted image 4 before by the way, but it belongs here too.
If I’m understanding this correctly, one of the early designs for 2-1B was later used for Jabba’s torture droid, EV-9D9.