Z axis depth indicator for Prusa i3; quick snap on

Hey there. I came up with this thing to quickly checking the level-ness of my print bed. I actually leave it on the x-axis gantry to check the height before each print. To check the whole bed, I:
1. lower the hot end to 10mm from plate,
2. snap on the indicator to check front left and right corner (the spring holder tab serves as a lever for release the clamping pressure)
3. move the bed forward
4. check the back left and right corner.
If I leave it on the machine (right side o