This is a remix of a model from designer Mylakovich Scifi RPG Heroes collection. It is a heavy suit of powered armor remixed with a helmet that I found on the internet. If might be all shiny and chrome if you paint it correctly.

If you want the cannon on the right shoulder remember to Mirror it in your slicer.

Check out the rest of Mylakovich's models on his page. https://www.thingiverse.com/Mylakovich/about