The X9E Module Bay kit by Cam Design allows the convenience of changing transmitter modules without removing the transmitter's rear cover.
While being a fun and rewarding project the Installation of the kit requires some intermediate modeling skills. For instance, the ability to cut a large square hole in the transmitters back panel. To get a better idea of the steps involved, see the installation instructions here.
The kit consists of two 3D printed module boxes. An internal antenna extension that allows the antenna to be mounted on top of the transmitter, rather than on the back. One Taranis module cover and 2 screws.