This is a remix of https://www.thingiverse.com/thing:1734129 by derailed. This is an excellent idea but I had a couple of issues.
If you have not seen derailed's original, you should go there first and read his summary for a full description.
The first issue I had was that it kept going under the contact which does not separate it from the battery. The second issue was that it is too easy to lose the part.
Both were solved by making it a permanent attachment (It can still be removed if needed).
It has 3 parts. To assemble it, first remove the battery, then place the insert over the main part and insert it in the hole as shown in picture 5. (Make sure the plastic is covering the contact and not underneath it.)
Then slide the cover on as shown in pictures 6 and 7.
This traps everything in place and insures it cannot slide under the contact.
Replace the battery.
The cover has supports built-in in the slots. I used an x-acto knife to cut them out and then a needle file to clean it up.