Keebio Sinc case, my special version

Modified from official Sinc case model, this version allows me to stack a numpad with arrow column on the right side of main keyboard. No PCB is broken.

(The problem I want to solve: there is no keyboard on the planet meets my requirement.)

In order to build this, except the printed model and keyboard component themselves, you also need:
- Enough M2 inserted threads that matches the holes. you can change the hole size yourself on fusion files
- Enough M2x16 screws to screw the case together
- The original M2 screws and standoffs that ships with Sinc. It's needed for right mid layer part.

Left Top Shell No Macro: Added key block that I don't need, enlarger screw holes for inserted thread.

Left Mid Layer No Macro: No change

Right Top Shell: reduce width by 1 column, and edge is smaller on the right side edge, enlarger screw holes for inserted thread.

Right Mid Layer: Remove the right side edge, right top and right bottom screws holes are larger for original screw standoffs.