Lens for Xero A1i Pro Bow Sights

Anyone figure out how to put a lens on an Xero A1i Pro Bow Sight. I was playing around with a 4X on my sight where I 3D printed an adaptor to attach the lens to the front shroud of the sight. Results are mixed and I'm not sure if it effect the dot location. Perhaps mounting it on the back might be better. The lens giggles around in the adapter I printed and it popped of at one point. I really miss my 4X lens on my Shrewd!  

Also, can someone from Garmin add a Xero A1i Pro Bow Sight Forum. Thanks all