So, it turns out the Internet’s sage advice that a 1/2″ EMT tube would fit into a 3/4″ OD PVC coupling is a lie. In fact, a 1/2″ PVC coupling is still too large >:O.
But! After a harrowing 90 minutes at the hardware store I discovered… a 1/2″ threaded pvc to 3/4″ slip adapter is compatible enough with threaded 1/2″ EMT so… the pvc adapter connects to the elbow, a set screw to threaded EMT adapter connects to the pvc adapter, and the conduit attaches to the EMT adapter.
At least the pair of adapters costs less than a single 3/4″ cotter pin, and it certainly is easier to deal with (build the elbows before hand, just tighten a screw to attach when I’m reaching for pieces above my head).
I guess I need to get some pvc cement… which costs as much as all of the EMT I’m using, so maybe I can find an alternative glue that will work acceptably for structural rigidity but not for pressurized water.
So now! After doing that whole “generating funds to continue paying rent” work thing tomorrow, more trellis construction. And pictures, finally.