This is a modification to YOCTOSUN Head Mounted Magnifier. This mod allows you to attach 2 lenses to the headset at the same time increasing the magnification. The original configuration of the headset only allows one lens.
For best strength, print on its side as is. Print with supports. I printed this in PLA and it worked perfect. Though I'm sure PETG would be a better option. The lens fit is very tight the first few times you take the lenses in and out, but then it loosens up nicely.