So most of the drive behind this project is to learn and grow from the original TinyPi. The TinyPi method of mounding the Pi onto the back of the PCB saves space, however can be a little tricky to get the solder to pass through and make a good connection. There is also the screen ribbon that can be a bit of a challenge.

The screen can easily be solved. There are many screens that are designed to connect to a zif socket. This will make installing the screen a trivial task of inserting a ribbon and swinging a lever.

Attaching the Pi is more of a challenge!! 

The 'normal' method of attaching the Pi would be to use header pins. The problem with this is that the space being so critical, the front face of the PCB needs to be kept clear for buttons, so that is a limiting factor. 

The next best option is to use SMD header pins, which could be pre-soldered during the rest of the assembly process. The problem with the SMD header pins is the larger then standard footprint needed would require more board area!!

While searching about I managed to find some surface mounted pogo pins. these would have an additional benefit of making the Pi attachment solder free!! this means that anyone could build the device, and make it more accessible to the masses. The downside of the pogo pins, is the additional distance between the boards. This could be used as an advantage, and the battery can be placed between the boards. So i bought some pins from everyone's favourite Chinese supply website, and did a test

now these pins are crazy tiny!! so I eventually managed to get those pins attached to the solder pads on the test boards i had

so with some screws and spacers, the pi can be clamped onto the back of the boards and connect to the PCB.

Maybe this could work.....