I do this, I use a plastic container, has a lid on each end, and when its full, warm it up in hot water, press on both ends turning the lids, works perfectly.
I bought this from the Bettaware catalogue some years ago, don't know if the still do it though, if not, maybe you can improvise.
What about Eternity Soap Lab,
They have some really lovely Soap Ingredients, for soap makers.
https://eternitysoaplab.com
Surely you will like these soap products:)