90 degree elbow to connect two pipes? That diameter? What material? PVC or metal? If its what I'm envisioning in my head, those should be even available at 7-11 or any other store around the block.. it must not be what I'm thinking, or of a diameter that isn't common..
I bought 2" diameter black PVC pipes to run computer wires and studio wires through.. ran one piece parallel on the back of the desk into 90 degree connectors that went down each side of the desk, into 90 degree, but with a 3rd side that could make a box.. its pretty cool.. I also have + shaped connectors and a couple of other shapes and have black PVC doing its thing hiding all my wires/cable power cords etc..
I bring that up just to show how common that sort of stuff is, but I may have a completely inaccurate mental image of what you actually need..
Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..