Okay, so I'm new to this forum, but I'm hoping I can get some help. I live in the United States, and I'm having trouble converting from metric to standard with the build plans given. I want to build the open source Spaceframe recumbent bike which the build plans can be found here http://www.n55.dk/manuals/spaceframevehicles/DIY.pdf The problem, the entire build plan is in metric, and I'm not sure about the best method to go about converting metric build plans to standard. Specifically, the build plans ask for 25mm square aluminium tubing with 2mm material thickness. Can someone maybe point me in the right direction as to how I should go about this build? Can I buy these materials at say Home Depot that would be the same size? Thanks for any help I receive. I have no degree in any kind of mechanical engineering, and I've only taken a beginners level physics course in college. I'm building this bike, because recumbent bikes are out of my price range to buy outright. This open source design is supposed to be strong, cheap, and effective.