Star Wars: Rare footage of screen tests with the unfinished droids (1976)

Those kinda resemble the droids you're looking for.

'It's March 1976 at Elstree Studios, UK and the props department are demonstrating the practicalities of the droid designs to George Lucas as actors Kenny Baker (R2D2) and Anthony Daniels (C3P0) familiarise themselves with the costumes and get used to walking in them,' writes 70sSciFiBoy. — Read the rest