I have mentioned before the issue with the batteries being loose - especially when placed on top.
I had an idea.
Perhaps future kits can have a set of four self-adhesive strips about 1cm x 8cm (4 pcs), that can be used to provide a friction surface for the battery holder. (two for the top, two for the back)
What say ye?
A small square of non-slip drawer liner under the pack might also work
I’ve seen small strips of self-adheisive “rubber” on devices and in kits as a form of foot to prevent the device from sliding. I suggested this because it may be common and inexpensive. I, for my instant case, am going to look for whatever I can find. Surely I have a few spare “feet” laying around somewhere!