I loved the Simple Metal Footprint by Thorped (Thing 593072) that I printed for my Simple Metal, so decided to design one for the Metal Plus keeping the aesthetics similar to Thorped's original design.
I found the Metal Plus to be a bit unstable when the build platform moves to its end-stops, this makes its much more stable and keeps it well grounded.
You just attach it to the printer using the existing screws.
Print the pads in any flexible material for best results.
3D Printing Reviews explains this modification in good detail, and can been seen here: