The handheld scale had escaped from it's sturdy metal ring somehow. Getting the scale back onto the ring proved tricky because it was hard to get — and to keep — the ring open. This small piece of PLA slides over a M6 bolt that was cut to size. Together with a washer and the nut I was able to pry the ring open easily, however. Simply turning the nut in the right direction forces the bolt against the other side of the ring and forces it open.

The design was made in OnShape, which I'm trying to master.