A personal project I did recently, based on the concept by Aggai Yakitate linked below. Be sure to take a look at their work! I created a base model in 3ds Max and used Zbrush mainly for smoothing and adding details with live booleans. Baked in Toolbag3 and textured in Painter. I also used a paralax technique shared by Ranulf Busby, for the holographic reticle in Toolbag 3.

https://www.artstation.com/artwork/2x9Glg

https://www.artstation.com/artwork/9eEnrO