DIY 6K Pro EF Mount and Lens Rear Part Support?

Does anyone tried to find a solution to make between their EF mount and lens rear part more strong?
In the majority of my shoots I am using 18-35, for more stability I am attaching smallrig lens support on the rods to hold any lens which I use during shootings.
I am focusing with fingers all the time and doing a lot of handheld.
Sometimes there is a play, which is normal as EF mount is not solid like PL mount.

Do you guys have a solution to make it more robust?

Attached pictures are not the best examples. Some of them are RF to PL adapters, but they can give you an a idea what I am asking and talking about.

3D printing works great, this is very solid and provides also solid camera installation

IMG_2930.jpg

It is not great if the lens needs to be changed frequently, but it sounds more like you will have the 18-35 mm on for long times.

This is closer to that which I want, but I would like to see other solutions as well.