There are basically two ways you can build this- design the body first and then see how great a challenge it is to cram all of the electronics in there or build your electronics and then design the body around them. I sort of took the first approach because I had a very specific look and feel I wanted in the finished piece. It was designed with the sensors and electronics I wanted to use in mind but I had to come up with alternate solutions as I built it due to space limitations. If I had to do it again I'd probably make it even slimmer and do all custom electronics to get everything to fit properly- maybe even add more sensors.
The method by which the end pieces are secured to the wood tube body is OK but could be a lot better. I'd make an insert and glue it into the wood body and have the ends either press fit or thread into them. It would be much more secure and look a lot cleaner.
I'd try to figure out a method for removing the SD card without taking the electronics out or have it work over WiFi. Removing the SD card as it is now is a bit of a hassle- my son can't do it by himself. A charging port would also be nice.