In the last update, black PBT keycaps were already in production.  How's that going?  Do you have any idea when we'll be able to buy them?  Can you share what the kits will look like?  I'm also curious about how things are going with the keyboard and other keycap colors, if you have any updates.
Thanks for your questions...
I'm hoping to have the keyboard done by the end of the year.
Black PBT is in production now -- China is just ramping up again after Chinese New Year.  The factory received the PBT material prior to CNY, but weren't able to finish production before their holidays started.
We're still colour matching White PBT.  No schedule on that one until we get the colour right.
To support popular colour combinations, we plan to have each keyset composed of 2 subsets (which will be available separately):  a Main Set and a Mod Set...
The 
Main Set is dominated by alphanumerics, plus other keys that share the same colour.
The 
Mod Set includes all modifier keys, plus additional keys of the same colour.
There are also a few duplicate keys that appear in both sets, to satisfy varying tastes.  This approach offers quite a bit of flexibility.  For example, you could combine a Black Mod Set with a White Main Set, or get both Main and Mod Sets in Black for all Black keys, etc.
Some keys will have duplicates in multiple sizes (e.g., 1.25u and 1.5u for Ctrl, etc.).
A rough list (by row) is shown below...
Main Set   F1-F4   F9-F12   NumLock   3 volume keys   F16-F18   Eject   4 pairing keys
   `~   1-0   -_   =+   Insert/Fn   Home   PgUp
   Q-P   [{   ]}   \|   Delete   End   PgDown   Num7-9
   A-L   ;:   '"   \| R2   Num4-6
   Z-M   ,<   .>   /?   1 Arrow key   Num1-3
   Spacebar   3 Arrow keys   NumZero   NumDot
Mod Set   Esc   F5-F8   Print Screen/F13   Scroll Lock/F14   Pause/F15      Delete
   `~   Backspace   Insert   Home   PgUp   NumLock/Clear/Tab   =   /   *   -
   Tab   W   \|   Delete   End   PgDown   -
   2row-Enter   2row-Num+
   CapsLock   A   S   D   Return   +
   L-Shift   R-Shift   1 Arrow key   
   2row-NumEnter
   L-Ctrl   L-Win/Option   L-Alt/Command   Spacebar   R-Alt/Command   R-Win/Option   Menu/Fn   R-Ctrl   3 Arrow keys