I drew this from scratch to make it easier to remix, but I tried sticking close to smitty's original design. Smitty's box is almost perfect. My only 2 complaints were the slots are a little too large to keep the smaller Betaflight 1s300 packs from rotating themselves around, and the lid was a couple mm too short for the same packs. I really liked the shape, the fact that the lid stacks under the box, and the “+” shaped hole method of organizing charged/flat packs.
This redrawing of Smitty's box is tall enough to fit 1s300 w/ the built in connectors. The lid leaves about 1/8" of spare room on top to add felt or foam padding if you so desire. It has 18 small slots to fit 1s300 (ie meteor65, mobula6, etc), and 15 large slots that fit 1s450 (ie mobula7 etc). The overall shape is similar to smitty's original, and about ½" longer and ¼" taller. The lid still stacks underneath.
I took liberty to make a larger international version of smitty's charge/flat legend on both sides. The legend is also on the lid, so it remains visible when the lid is stacked under the box.
Printing is basic… I used PLA 0.3mm layers no supports. You could do the same, or maybe PETG in case it gets left in a hot car or something.
[edit: 3/10/2023, I just received my first 1s450 GNB packs, and the slots were too small. So I made some adjustments and re-uploaded the stl files. Sorry if this was an inconvenience to anybody who may have printed prior.]
[edit: 6/10/2023: I recently bought some Webleedfpv 1s300 packs that were a shade too thick to fit. So I widened the small slots and uploaded “whoopLipoBox2.stl” and “whoopLipoBox2top.stl”. This version will fit the newer 1s300 folded packs even after some swelling happens, and still fit the old Betafpv packs well. While I was at it I added 3 more “T” shaped slots to the large pack side of version 2. They aren't meant to fit lipos, but can hold some whoop related tools and accessories. Last but not least the notches to hold the lid on my original design were too loose for just tossing in a backpack without adding a strap to secure it. So I beefed the notches up on version 2, to give the lid a more "travel resistant" fit.]
The author remixed this model.