Unfortunately, it became so big and heavy, that it is more something to put on your desk as a clock and have it send text messages on all kinds of events. Or receive text messages and perform actions upon receiving. Also, battery life is not good. The 8 rechargeable penlight cells will only last for 3 hours.
I tried to use off-the-shelf components as much as possible, so no hard to get li-ion battery packs, but plain and simple penlights. and mini USB to provide power, so any usb charger will work.
I took the pi, removed the rca and earphone plugs then drilled a hole in the tft PCB, so i could solder the pins of the pi onto the tft pcb.
The Arduino gsm shield is almost as big as the pi , so to stack one on top of the other seemed the most logical way of putting it together.
To get some kind of shielding between the GSM antenna, and the pi, i decided to make the case out of "etch it yourself PCB". The casing is made in compartments, not unlike the Matryoshka dolls [http://en.wikipedia.org/wiki/Matryoshka_doll].
The first cup was to hold the electronics to charge the batteries on the inside, and to hold the GSM shield on the other side. There are two "power suplies" (dc/dc convertors and voltage regulators). And you realy need to power them both to charge the battteries and power the pi and GSM shield.
To give the antenna free "line of sight" to a GSM tower, a second cup was made, with a plastic bottom.
Then another cup was made to hold the first cup and mount the batteries on.
And then a last cup was made to hold the display and pi. The pi was placed in the topleft corner of this cup, so the USB and HDMI connectors are still usable.
And to finish it off, i used teak veneer, to make it look more decorative.
I hope it will inspire someone to make a better, smaller version, with better battery life.
The old site is here