ER8M wrench

I used t4deusz's design (https://www.thingiverse.com/thing:2665470) and it works. I did find it annoying to use with my Ant however.
So I made a wrench which is a bit longer and has thinner edges so it can fit between the Z-axis holder and the collet. That way you don't need to lower the Z to do a tool change.