This is designed and tested with 19mm Therm-App lens. Other lens "might" work.

I been using PET-can-cap-made improvised-protector forever. As soon as I got my Pruse i3 MK2 I start working on real lens protector. This is what I got after some try-end-error. And this is actually my first self-designed item :)

You can see the evolution of my Therm-App lens protector in photo.

I print this with X-axis or Y-axis rotated 180 deg. I suggest you do the same.