Generic Calculator Shield for Arduino Photo-journal

[sa-penguin]

If you want a pretty end product, you will probably want slim(low profile) layout.
If you want low profile, Arduinos and Beaglebones aren't the best choice.

The Edison, and the Raspberry Pi Compute module, use a SIMM style connector. In theory, you should be able to get a keypad and display onto a custom interface board, with room left for a flat LiPo battery, without getting too fat.

To do the same with a Due (no shield connectors), you'd have to redesign a custom board. Possible, but more of a headache.