What shipping size to use

Well I have my first clutch, that I am getting ready to start selling/shipping.

What size box should I use to ship baby bps in? And do you recommend a deli cup or bag for babies? (By babies i mean under 300g)

I am trying to get my packaging supplies in order.

It depends on how many animals you're shipping. For just a a single to a couple of snakes I use the 12x9x6 and go up from there depending on how many I'm sending. And I ship hatchlings in 8oz deli cups with a little bit of aspen. If they don't fit comfortably in deli cups then they go in bags.