RE: How to build dummy ww1 1/3 spandau guns
I can speak for their Spandau kit, but I've built their Lewis Gun in 1/3 scale. It was nicely done, just very basic, not much detail.
You might also consider Arizona Model Aircrafters Spandau kits ($59.00/pair). While not totally accurate, there's a nice amount of detail, and they (at least used to) come with leather MG belt and brass shells. You can view the instructions on his web site. That being said, a word to the wise, if you decide the AZM route, make sure they are in stock before you order, or you might wait a long time to get them.