I needed to attach a mini educator dog training tool to a 25mm collar, but the standard collar size is only 20mm. Printed a new cover with 25mm collar channels. Reuse the gasket and the screws from the original cover plate when installing. It's a tight fit insight with the battery etc, but this is important so that it doesn't bounce around and get damaged. You can see from the photos, this print has been used and tested. Ideally print from PETG or PETG-CF (as the cover image is) so you've got impact resistance. PLA is likely to crack.