This is a short endcap/muzzle break/whatever for the Gryphon by Flygonial. The original idea came from Taffy, designer of the Skewer. There is a standard version and one for the “carbine” Gryphon variant which has a larger bore at the end of the barrel.
Edit 10/21/2022: Slightly increase size of bolt holes to avoid threading into this part (only the cage pieces should be bolted into)
The author remixed this model.