Đầu mài pin 18650 cho máy Dremel

This attachment is adapted from DaniRP's model.
I thought that cleaning up the center of the button and bottom maybe was faster if the axes of cell and and grinding stones were not aligned.
I offset the center off the cell slightly from the center of the grinding stone.

I have an 8250 Dremel, but I assume it will fit most Dremel rotary tools with similar thread.

This attachment uses a ~10mm grinding stone with a flat end.
Some of these grinding stones are hollowed out on the end, I dressed the stone flat using steel grit on a glass plate. A diamond dresser or a dressing stone, e.g. Dremel 415, should work also. 
(A dressing stone is good to have anyway, to recondition or reshape your grinding stones.)

Printing
I printed in ASA with 0.6mm nozzle, 0.25mm layer height and 20% infill.
A brim to help attachment to the bed and organic support for the top of the 'window'.

Feedback for improvement is always appreciated!
Bart