We were asked to recreate the transponder boxes that are used at tracks for guys that need to borrow a transponder. This is what we came up with. The boxes come in two different sizes depending on your application. The flat, more squire box is closer to the original track transponders. Sizes are below. These units have been tested and are very durable. They are made with a 3d printed body, carbon fiber lid, aluminum body post, and 3m hex head screws. The boxes securely hold the transponder and battery in place. In order to charge these batteries and to unplug the transponder, you will need to remove the lid each time. With this transponder and battery combo, you can run them all day and not have to worry about them discharging completely. The battery this is designed for is linked below as well.
Flat Box Design: 29mm tall (not including body post), 53mm wide.
Tall Box Design: 33mm tall (not including body post), 51mm wide, 33mm deep
Lipo: https://www.amainhobbies.com/protek-rc-2s-high-power-30c-micro-lipo-battery-7.4v-240mah-ptk-5185/p169479