A four inch deli cup should suffice. You don't want too little fresh air intake and this size will enable you to better the temps from cooler to a warmer place. Depending on how old the scorp is. I have one that is every bit of a year old and a few months and she is only about twice the length of a dime crossways. I've been keeping this scorp at exactly the same temp and humidity as the adult for the entire time I've had her. I use a small, very thin piece of slate in the cup which she always hides under, except at night, when I throw the occasional pinhead cricket in. I keep her on sand because it holds up the slate better and the scorp is much smaller than the stone... by at least ten times, and is very unlikely to burrow out the entire area under the slate.