I have Vention HDMI to RCA converter (https://www.alza.cz/vention-hdmi-to-rca-converter-black-metal-type-d5858219.htm) I am using for connection to my FPV headset. It was laying around my PC for a while until I figured it would be best to have it just under table.
It's not complicated geometry but impossible to print without support (sadly). I printed mine in same orientation as it is going to be mounted on desk to ensure internal dimensions are correct and not distorted by supported surface so mounting tabs are supported.
Material doesn't really matter, I usesd PETG just because I have it laying around.
The author hasn't provided the model origin yet.