I like the idea of small, portable keyboards. The JD40 is nice but the giant space bar is a waste of space and it is difficult to type in german. So I made some modifications to the default JD40 without increasing size. I split the space bar and make it smaller to get two more keys in the lower row.
One of the space bars is used for the green layer. I use only the right thumb for space so the left one is the modifier. On the green layer are the numbers, the german umlauts, the ß and some commonly used characters, but I will do some optimizations. The default function of the top left key is Tab and the option is Esc. The default of the top right button is Backspace and the option is delete. In a later version you can swap default and option. The red layer is QWERTZ default.
The blue layer is inspired by the Neo 2 Layers 3 and 4. I moved the motion keys to the right hand. So you can move the cursor without leaving the home row. There are also backspace, delete, insert, pgup, pgdn, home and end. The rest will be characters for programming like [] {} and so on
I will also add options to swap space and the green Mod, swap green Mod and Shift (if you like thumb shift like me) and swap the left blue Mod and Ctrl
The Fn layer is not defined yet, but there will be the F-keys, volume control, some other funktions and maybe mouse control.
Because the layout is not finished yet I will post the link to the Keyboard Layout Editor instead of an image.
http://www.keyboard-layout-editor.com/#/gists/bc4bed854a76e9fb2d16Please let me know what you think or what could be better