Hello there! Nice to see professional illustrations on RRU : ). I don't really remember many other comparable examples on this site (there are more examples from other sites like DeviantArt). A few years back (2 or 3?) a comic artist posted a picture of the Granite Grinder (and probably other pictures), but there wasn't any further activity. RRU also has an art thread (and sometimes members made separate ones), but they are basically all inactive now (I tried to revive one, but it didn't work).
I like the addition (or rather change) of the mechanical arm since the original was just a simple turquoise pipe (to be fair: it's a minifigure and the print options were more limited back then). In theory you could argue that a protective cover like for industrial robots would be more realistic, but on the other side it would just look lame and like something wrapped in foil XD. By the way: Is there a part that you personally found the most challenging or interesting?