I wouldn't be quite so quick to dismiss scratchbuilding. It sounds daunting but when applied to a structure like a station canopy really isn't.
For me, the difficult part is arriving at a drawing. Once you have that, think about it in its component parts and map it out on the pc for accuracy.
I don't know exactly what you want, but the Scalescenes kit might be an excellent starting point. Because of their nature, the kit is very easy to alter to suit what you want.
Card is a great modelling material and I use it for a lot of scratchbuilding.