Linear Bearing Mount for LM12LUU 12mm rod diameter

This is my first attempt at modeling something useful.
The LM12LUU linear bearings came without a mount when I bought them online, I decided to make one, after a few attempts, this is what I came up with.

The measurements are:
Bearing length = 57mm
Bearing outer diameter = 21mm
Bearing inner diameter (not relevant for this part) = 12mm
All screw holes diameter = 3mm

The screw holes are 3mm, I found out that I could use the bracket holes that keep the part closed without a nut on the o