Custom Y branch duct fitting

[rsuppa]

I'm attempting to make a custom duct part. It's to be a supply air Y branch - the duct off the unit will split left and right into two differing and smaller duct sizes. 

Example: A 24x12 duct splits at a Y into a 12x10 and a 18x12. 

I was able to produce a Y branch by drawing two line arcs and making use of the custom duct fitting function that had all the same duct dimensions - starts as a 24x12 and Y's into two 24x12's. Unable to have the branches smaller.

Am I trying to do something that's not possible?

[Tiana_Y]

Hi @rsuppa, 

Thanks for posting in the Forum! How did you go about creating the custom duct? Could you create a 

 quick Screencast video?