I remixed Ashf144's file on Thingiverse to nearly eliminate the need for supports and improve the overall look (in my opinion). I also added a bevel where the battery clip goes to help it slide into place better and more easily. The only place where supports would be needed if printed upright is just at the bottom under the rounded corners. You could probably print it without supports, but you might have a little bit of sagging on the first few layers.

Orientation: print standing up as shown in the picture.