What is this???

[mklotz]

My guess is that it is a bit of salvage that he was using to count some workshop event he was interested in tracking. Examples might include:

number of times a special tool was used
number of times a certain operation was performed
number of hours he spent on a certain job

Like the jigs of unknown purpose one unearths in one's own shop from time to time, our heirs will find lots of bits that defy description. (I've even maliciously planted a few to really confound them.)