does anyone have a guess on how this was done?

ABecause of it's size, i would think that only the cube is made out of cake, covered with fondant by panelling. Bumblebee looks like he's made out of molded RKT covered in modelling chocolate or fondant. You definitely have to have good solid support to pull this off, maybe PVC pipes? Like the ones they use in cake shows? :)

AOh okay. When covering molded RKT will the fondant stick to the RKT or will I need to "glue" it frosting or something?off topic, your profile picture is beautiful! :-D

ACarlos Lischetti has a similar model in his book Animation in Sugar. His is a robot but similar in shapes etc. Carlos makes his entirely inedible as a cake topper, it's made from styro, pastillage, skewers and wire. I would probably go this way too, and then given the cost of this piece (the number of hours it would take are incredible), the client could at least keep the topper.

A

Oh thaks :) yes, you would have to coat your RKT with buttercream to act as glue to help fondant adhere to it, also roll your fondant thicker to have a smooth finish (no bumps from the RKT).

I would also agree with the winniemog, you can go with the inedible topper route. Less stress i think as you will have stronger structures with styro and wires. Or if it was MY customer, i'd ask them to provide a toy.. Hahaha i suck at making figures :(