Hi Stevan, Several different versions of the spring 'h' clip come to mind. Visualize the letter 'C' reversed and the letter 'C' facing forward. Push both letters (reversed and forward) towards each other. If they are attached at the touching center portion you now have a two sided clip.

Now lets make a super large scale version of the clip with a wire bending jig. You will need a piece of wood, hammer, finishing nails, wire, wire cutters and a marker. With the marker draw a large letter 'H' on your wood. Drive a nail into the wood at each of the further most marker strokes (top and bottom points of left and right legs) of the 'H'. Drive a nail at two points where the center stroke touches the left and right legs.

Now comes the wire bending. If we are holding the jig upright in the 'H' shape we will take the wire and run it up or down the left leg, then reverse the direction by 180 degrees and come back to the center of the 'H'. Using the center nail as a pivot point make a 90 degree bend across the center portion of the 'H'. Upon reaching the right leg of the 'H' we use the center pivot nail and make a 90 degree turn extending the wire to the top or bottom of that 'H' leg. When we get to the top or bottom we use that nail as a pivot point and reverse the wire bending it 180 degrees until it reaches the other end of that leg. We then clip the wire with our wire cutters which is now 'H' shaped. We now have a very primitive, large 'H' clip. If the wire is steel we could then temper it for the spring tension. Metal strapping would also work with this jig.

After making the large sized 'H' clip you can reduce the size of the jig and scale it down for the material you are using 1/2, 5/8, or 3/4". By altering the angle of the upper and lower portions of the legs on the 'H' you can create the 15 to 30 degree angle the roof and intersecting side joints use. If you wanted to get even more ambitious you could make a set of male/female stamps (easy enough to do) for the wire shaping instead of using the wire bending jig.

As a point of interest.... look at a clothe pin and its spring mechanism.

I think something that might even be simpler than the 'H' clip would be using some PVC tubing (3/4, or 1" dia.). Cut two lengths and glue to each other (like a double barrel shotgun barrel). If using EMT, it could be spot welded or bolted. The length of each can be whatever 2", 3", 6" or as long as you like.... Cut a groove the length on both outer sides. It should be just slightly smaller than the size of the material you are connecting. Slide these connectors on to both pieces of material. Then tape. Should make alignment very simple.