idler pulley mount for M5 bolt hole, mounts on 2020 or larger v-slot

This is a simple mount for attaching to a 2020 or 2040 v-slot rail, to hold a single 5mm bore idler pulley. I needed this for my installation of a 3-leadscrew Z axis system on my D-bot.

It's useful to help take up the slack if a belt is a little longer than needed, or to change the direction of the belt, or whatever.

A much smaller and more compact mount could be designed to hold a single 5mm bore pulley, but I just started with the Z axis bearing mount assembly that I'd remixed as part of