In the mean time study this “abstract” beam section at some Mesh Edge. Using a rect profile (the red) … well … it could make things a bit complicated - for no reason - in case that you want to do some sort of leak-free envelope (even a mini-demo one with glued glass tri panels). Remember: the scope of any dome is to support some envelope.
Note: the 2nd red profile shown is indeed used in trusses done via, say, a ZK-Mero System. But this requires complex and very expensive hinged alum systems like the one below (I suspect 1M miles away from what you have in mind for your mini/demo dome envelope):
