There are a few double angle shapes I need that I have not been able to properly create. I've tried rotating single angle shapes into the needed orientation to create the double angle, but when trying to place the shape only one side is displayed.
The steps required to create a "combined" shape - the ProStructures term for a double shape - are outlined in this wiki. To summarize:
First, place two angle shapes side by side with the desired gap in between, viewing their cross-sections from a top orientation:
Next, following the steps in the wiki, create a new catalog such as "Custom Double Angles" containing a new combined shape we will call "Angle001":
Once the information is saved, after restarting OpenBuildings Designer that new double angle should now be available for placement: