Copy and paste this text in to notepad, use it to help you make a bit mask for choosing which drives to restrict in Group Policy

 CCCC U   U RRRR   RRRR   EEEEE N   N TTTTT
C     U   U R   R  R   R  E     NN  N   T
C     U   U RRRR   RRRR   EEEE  N N N   T
C     U   U R   R  R   R  E     N  NN   T
 CCCC  UUU  R   R  R   R  EEEEE	N   N   T
___________________________________________

***********
*No Drives*
***********
Drive Letter		|zyxwvutsrqponmlkjihgfedcba
W Student		|
WC Staff		|
CU PowerUser		|

*******************
*No View of Drives*
*******************
Drive Letter		|zyxwvutsrqponmlkjihgfedcba
W Student		|
WC Staff		|
CU PowerUser		|



N   N EEEEE W   W
NN  N E     W W W
N N N EEEE  W W W
N  NN E     W W W
N   N EEEEE  W W
_________________

***********
*No Drives*
***********
Drive Letter		|zyxwvutsrqponmlkjihgfedcba
W Student		|
WC Staff		|
CU PowerUser		|

*******************
*No View of Drives*
*******************
Drive Letter		|zyxwvutsrqponmlkjihgfedcba
W Student		|
WC Staff		|
CU PowerUser		|