Raspberry Pi zero mini system.

Screen: http://www.ebay.ca/itm/3-5-Inch-TFT-LCD-Car-Rear-View-Monitor-Color-Screen-DVD-VCR-For-Backup-Camera-/251946543362

I was lucky to find that this has a 3.3v spot so no need for modifications. 

Charger and booster : 

http://www.aliexpress.com/item/0-9V-5V-600MA-USB-Output-charger-Mini-DC-DC-Boost-Converter-TP4056-1A-Lipo-Battery/2038845625.html

Rocker Type Switch: http://www.ebay.ca/itm/5Pcs-Small-Size-2Pin-Black-Rocker-Switch-6A-250V-ON-OFF-SPST-KCD1-101-/171329602644?hash=item27e40a4454:g:~ZwAAOxynwlTc2iK

Battery was removed from a broken tablet but you can use any size that will fit into the space. 

All Parts can be downloaded from my thingiverse section at http://www.thingiverse.com/thing:1568133 Wiring is Very easy.

 worked in a raspberry symbol into the controller