I have modified the original model by Funbie Studios so that the attachment fits in my massage gun (Bob & Brad brand).
2 extra silicone o rings were in the box that I have used in the 2 notches so that it fits securely.
I would recommend you keep your hand over the bottle while you use this as some might be a little loose and come out while being shaken. Vallejo bottles for example are a tiny bit smaller than reaper ones.
The author remixed this model.