Movies make weaponised robots look easy to build, especially if aliens do it. Watch movies online for free about these steel monsters, and be amazed by the precision in how they were built.
The popularity of robot heroes has gone cultural. In 2009, Japan celebrated the 30th anniversary of the popular Gundam franchise with a 1/1 scale of the RX-78-2 Gundam. This so-called "mecha" is the first of a long line of Gundam models, featured in the anime series Mobile Suit Gundam in 1979. The statue stayed in Tokyo for a few months before it was dismantled.
Of course, this isn't a working robot, but it raises an interesting question. How close are nations to developing "mobile suits" (as the franchise calls them) of their own?
The idea of weaponised robots aren't new. In fact, it began with French writer Jules Verne in his late 19th century book, The Steam House. He mentioned a "mechanical elephant" used to transport people across British-occupied India following the failed rebellion in 1857. The modern mecha, however, is largely attributed to H.G. Wells' tripods in War of the Worlds.
For now, the closest thing to mobile suits are mechanical exoskeletons. The Power Jacket MK3 is one such example, allowing humans to carry up to 15 kg of goods, and walk or run for longer distances (although the manufacturer set the limit at 2 kg for safety reasons). If you have more than $100,000 to spend, you can get one of your own.