Hi, in the file section (tools dir) I uploaded a picture of my hand 
made tip gauge. I used a tick glass I bought in a Brico center (it was 
for decorative arts) and a device commonly used to measure the deep of 
used tires...
The sesitivity is about 1/10 (mm).
Cheap and functional... (at least for me)
Best regards,

Dan

P.S. a more complex device will be posted soon.