Here is a photo of my completed Xylophone.
A cross section drawing would have been a better way of describing the construction.
The bars are made from Australian Blackwood. (more commonly known as Tasmanian Blackwood, Acacia Melanoxylon.)
The sound box was made from Julutong. (Dyera costulata). I did not use any nails. I mitred the corners of the box. (The sides were increased 1" to allow this). Where additional strength or support was needed I used hardwood pegs. The finished box joints were fully airtight so no filler was required.
The sticks were fitted with rubber chair feet. I was unhappy with the sound so turned up a couple of balls from some western red cedar. (this is soft wood and will not mark the bars.)
The whole project was finished with Kunos natural oil finnish.
Tuning was problematic in that temperature changes effected the notes. i.e., immediately after sanding the end of underside the note would be spot on only to change five minutes later once the wood returned to its former temperature.
The xylophone is now tuned successfully and works a charm.
I thoroughly enjoyed the experience. My grandaughter is thrilled with her new instrument.