Hello and thanks! I apologize in advance if I picked the wrong place to post this thread. I'm a high school student building a Rubens tube and have encountered a problem: I have a one inch outside diameter aluminum tube. It turns out that the one inch copper reducer and PTC I bought is actually 1 and an eight inches using the standard imperial system. For some reason... the one inch for each metal is different! Ugh! I request help. Aluminum is used for curtain rods and building light materials. As a result, it does not have PTC adapters and reducers. Where can I go for fittings that follow the typical imperial system? I've visited home depot and they only have copper fittings and pvc ptc fittings are illegal anyway. Any work-around solutions are also welcome! Side note: PTC adapter is a push to connect adapter for connecting plastic tubes into.