Slimline SATA adapters
1) Is it possible to make a female Slimline SATA to female mSATA adapter for SSD?


I believe this is possible.  The Slimilne SATA uses a 5V power input alone.  I'm not sure, but I think that the mSATA uses 5V as well as 3.3V You would have to implement a 5V to 3.3V regulator.


  2) Is it possible to make a female Slimline SATA to female microSATA adapter for SSD?


See response for #1


  3) If either one can be made, what voltages could it output?


See response for #1


  4) If either one can be made, how small could it be?


Entirely depends on the skill of the engineer who lays out the board and also the power supply.  You obviously need space for the two connectors.  You'll also need the power supply on the board.