This is my take on a base-mount for the Arduino/RAMPS 1.4 electronics for a Mini Kossel 3D printer. I found that the ones available just didn't quite fit my electronics, purchased from AliExpress. This is designed for a 1515 beam mount and gives sufficient clearance from the frame to feed the LCD ribbon cables frontwards and between the mount and the aluminium frame so that everything can be hidden inside the electronics console out front. I find that the height of this with RAMPS/Arduino boards installed, and the ribbon cables too, is just even with the plane of the bottom of the print bed. The pictures are of a slightly earlier version without the crossbeam brace that's present in the STL. I print this with support enabled, to make it neater, as it has a bit of overhang. I use 6mm metal screws for attaching it to the electronics boards, as the thread self-cuts and grips the plastic well.
Download from thingiverse