My Transporter batter had an insulator base but no cover over the positive battery terminal. Mostly they get lost along the way and serve little purpose, but it's just one of those annoying little things that's an easy fix.
PETG is probably OK in this situation - it's not a super-hot area, but I've printed this one in PLA as a test until I break out the next spool of ASA!
Simple print, no supports.
The author marked this model as their own original creation.