I had a nice box from a RunCam laying around and thought it would be perfect for a battery holder. So this is it. Obviously this would work great sitting on your desk as well. It holds a mix of 550~ and 230-260mAh batteries.

Here are the dimensions I used:
8.1 x 17.1 = beta 550 lipo
7x 11.7 = 260 GMB red lipos, nitronnector, betafpv 260

Box outside size:
86x67mm

Designed in OnShape:
https://cad.onshape.com/documents/4d338af58d3f9456814e4a57/w/b15b9c604155ed14501c6888/e/5cfedeb21da3efb9193fa198