This was designed by me for a rpg setting called GREP, which was written for the EABA RPG system. GREP is a RPG setting featuring alien nanotech arriving on earth and diffusing thru the ecosystem, and eventually becoming usable by humans. This was meant to represent a nanoscale assembler/disassembler built by GREP to fulfill an order.
While it was never used in the game the author allowed me to post it here.
The body was based on a rod bacteria, the arms were inspired by a squid, with two large ones for brute force manipulation while the 4 smaller ones allowed fine adjustments of position.
The tail fins were propulsive flagella that was meant to not only rotate like a propeller but undulate like a moray eel propelling itelf thru the mater for maximum effect.