Kern balance battery insert

## Replica of Battery Insert PWS-A01 ##

This is a replica, or at least, a working substitute, for the battery
insert PWS-A01 for the
Kern PWS 8000-1, PWS 800-2, and PWS 3000-1 precision balances.
Actually, I've never seen the original part, but printed it since
it is clearly overpriced (over 100 EUR). It looks more or less
like the product pictures, and does fit in my PWS 8000-1.

Original files can be found at [here](https://bitbucket.org/staffanulfberg/plasticpvmparts/src/master/kern-scale-battery-holder/)