These stackable battery holders are a design I did for Checkerboard, Ltd. and were a Quirky.com community selected design. Checkerboard gratiously allowed me to post them here on Thingiverse - if you're interested in getting them printed on a high res printer, please support their hub on 3Dhubs! There are three sizes available. Each size has three files. Download the files for your size. I recommend printing and then hot-gluing the parts together. They are friction fit and include tabs to ensure a tight, permanent lock.