I've 3D printed some brackets to fit a SONY XAV-AX3005DB, I'm sure it will also fit many other Sony HeadUnits too but check with me first.
The brackets are made to order, so basically I will print a set if anyone is interested. Alternatively if you have your own 3D printer and want to make them yourself, you can find my STL files for free in thingyverse:

Colour: Black or Gray, alternative colours contact me.