For all those out there still searching for an R2 unit to put in your 1/24 SS models, I finally found one.
Assuming that a diameter of 3/4 of an inch is correct, there is no need to buy an entire Star Wars chess set to cannibalize a single piece. Just go anywhere that sells Star Wars figures, and pick up the R2-D2 keychain. It looks like Hasbro packaging, but is made by Basic Fun. I see these keychains everywhere, yet I can't find ANY info on them online. I picked one up at Toys R Us tonight for $3.99, and it measures a perfect 3/4 inch diameter. Detail is pretty decent, and if recast in resin and cleaned up, could look very very nice.
Here's a crappy pic I took with my phone: