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Next comes gluing. This must be done in a very well ventilated area, I'd suggest going outside. I didn't use primer, you may want to. Follow the instructions on the cement for actual technique. Remember to keep the positions of pieces correct when putting this together, and don't get them rotated wrong. I'd suggest putting the short pipes into the corner fittings, then the corners on the outer long pipes, then the tees on the inner long pipe, then then add the outside long pipe assemblies to the middle (this requires doing 2 joints at once, so be quick), and finally add the bushing reducer.
The brass fitting screws into the plastic threaded bushing. Pipe threads are tapered, they should get tighter as you screw them in. If the fitting doesn't get tight, it probably doesn't seal. Mine got harder to turn when the hex part you grab with the wrench ran into the plastic, do not mistake this for it getting tight.
You should use teflon tape to wrap the threads to make it fit tight, but I just used hot glue to seal around the fitting, this should work for a vacuum system.
