Acrylic Soap Molds

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Sep 20, 2019
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I recently bought Wild Platanica's square pull through plates which are made to fit in the quart dairy containers. I really like them and the smaller square size of the soap. But my problem is... I do not buy a lot of those dairy containers or use the dairy products when I buy the containers. I could make lots of homemade butter and freeze it I suppose... 🤔 So I want to make my own molds. But I cant decide what material to use. Wood would be the easiest to build, but the hardest to use... lining and sealing/capping the bottom. Acrylic would be cool and I know there are acrylic molds out there. But all the YouTube videos on building with acrylic warn to keep away from heat. Does soap get hot enough to melt or warp acrylic? And my last option is HDPE, which I think is best, but is all HDPE grainy like cutting boards? Will my soaps edges have a texture? I'm finding company's online that extrude 3" square acrylic tubes, but they are quite expensive! $30 bucks a foot & sold in 6 to 10 feet length. The are pretty though... nice curved corners, that would probably not fit my 2.75" diameter plate.... just thinking out loud here! Any suggestions greatly appreciated!!!
I have an acrylic mold from Custom Craft Tools, and they say the upper temp for their molds is 239-266F. I gel my soaps and have never had a problem. I use heating pads and insulate rather than the oven, but CCT mentions CPOP on their website. I don’t know if there are different grades of acrylic and if there are, how heat affects it.
is all HDPE grainy like cutting boards
No, HDPE can be very smooth, and in fact is used in a lot of applications where smoothness and low friction are required; it's sometimes referred to as a self-lubricating plastic. Have a look around YouTube, there are lots of videos of people remelting HDPE to upcycle it into new forms, it's one of the safer plastics to work with at home.
I could make lots of homemade butter and freeze it I suppose... 🤔
Difficult from homogenised milk. Cheese is probably more promising. But in either way, you'll have to deal with a lot of buttermilk or whey. Kefir is another alternative – a friend of mine goes through a milk carton every day with that.

But does it have to be a dairy carton? Around here, they're selling about any beverage in Tetrapak, including almond/oat/soy/rice milk, coconut milk/water, tomato purée, fruit juices, cheap wine, eggs, coffee, iced tea, vla (warning: addictive!)… I can't imagine there is nothing that is of any use for you (or your family/friends/neighbours/kitchen of your favourite bar…). Reuse the cartons, then you don't even need a constant throughput.
I made a rectangular column mold with legos (it took a while) and then made a liner with a plastic chopping board from Dollar tree. I am not suggesting you do this, but only to point out you could do a wooden mold, and find a way to line it for easy removal. You can tape the liner to avoid leakage and pull the soap up. However, a removable bottom plate in case there is leakage would be nice.