Ultimaker Grip Feet

I have my printers on a metal shelf, which is convenient, but I find the wooden feet of my Ultimaker Original a bit slippery (I've had more than one close call). I made these feet attachments that can be printed in a flexible material to provide better grip strength and less sliding.

There are two feet, one foot for the front right and back left and one foot for the front left and the back right. They can be printed in basically any flexible filament. I used WillowFlex, but NinjaFlex, SemiFle