Lineart of the cover mecha from the tabletop-wargame-with-Lego-robots Mobile Frame Zero.
Buy a physical copy or download the pdf for free here: [link]
The design was strongly influenced by the B-ATM-03 Fatty from VOTOMS (it's not called the 'Chub' for nothing).
For the actual Lego models, just search for 'chub' & 'lego' on dA.
Mobile Frame Zero, Rapid Attack, and Micro Construct Tactics Nova are ™ Joshua A.C. Newman of the glyphpress.