use existing bag if correct shape. best is a hardsided old samsonite or equal. they are available cheap from second hand stores like salvation army.

get the mache(dividers) out of burgundy/champagne boxes.

fill the suitcase with towels(they got towels wherever you live?)

throw some tape around the whole case.

it will probably be opened by TSa, but they will retape.

do NOT tell UA gate agents what are in the suitcase. many do not know the rules, and think that alcohol cannot be shipped at all.