A little late in getting this out, but still worth mentioning. Mega Minis has release their lovely Demo Bot in 15mm. A faithful reproduction of the original 28mm version, this robot would make a fine addition to any science fiction board.
It comes with an assortment of arm options so that you can weaponize it or field it as a simple utility bot.
If you are a multi-scale gamer, fear not as this gigantic bot is perfectly suitable for use with your 28mm minis as shown below.