Just uploaded a simple but handy battery holder that fits four 9V batteries! Designed with holes for the positive and negative terminals, so you can easily wire it up or add connectors. The lid snaps on to the case for a tight and strong enclosure. Perfect for DIY electronics, Arduino projects, or anywhere you need a compact 9V power setup. Prints cleanly without supports, and fits standard 9V batteries snugly. Give it a try and let me know how it works with your setup—feedback always welcome!

Description: Here’s my 3D printable Klein Bottle, a mind-bending shape with no true inside or outside! It’s a physical representation of a mathematical surface that can only exist perfectly in four dimensions—but this version brings it to life in 3D. Perfect for math lovers, teachers, or anyone who enjoys impossible geometry. It makes a great desk piece or conversation starter.