July 7th 2024:
I have since updated this to refine the PTT guard a bit more. See V 1.15. Print it using 0.12mm layers. I plan to use B-7000 adhesive to attach it. I used 3M doubled sided tape on the prior and that worked well.

I also added an updated knob guard, V3.7. This needs support. I increased the support to model distance to 0.25 mm which helped make it separate easier.

Here is a PTT and Knob guard to put on your TYT MD UV-390. It helps prevent accidental bumping of the buttons and knobs.

To install removed you antenna and pull straight up on the knobs. Plus the knob guard on the radio and reinstall the antenna and knobs. No need for glue, the antenna and power/volume knob hold it down. You could probably add an o-ring under the knobs to add further tension if you needed it. It will fit an antenna with up to a 16mm diameter.

The PTT guard will need to be glued on with adhesive. I will experiment with some good 3M automotive double sided and see how that works before I resort to a small bit of epoxy.