What can I reuse or recycle to make soap moulds?

I made my first batch of cold-process soap earlier in the year – it took FOREVER to trace, but we’ve loved the resulting soap so I need to make some more.

Ever since I made that first batch, I’ve been on the look out for what I can use as moulds this time around. Last time, I had two old food trays for bar soaps, but when I ended up making a lot more soap than I’d originally intended, I grabbed whatever else I could find – some shaped fruit trays (small hand soaps), an old round ice cream tub (too wide when sliced into discs so had to cut them into semi-circles, which was a bit odd) and the square edged plastic bottles the olive oil had come in (nice size hand soaps, but it was awkward to get it out). (The latter two can be seen in the picture.)

All sorts of packaging has been subject to my “would it make nice soap?” eye. A few weeks ago, I was reading about someone else’s soap making on Simple, Green, Frugal and she mentioned using poster tubes (with the bottom sealed up) to make nice sized round soaps. As we’ve not had any posters or the like delivered recently, we haven’t got any of those but it got me thinking about similar cylinders: a litre-ish, straight-ish juice or pop bottles would probably about the right size, although it’d probably be awkward to get out like the olive oil bottle. That led me down another juice line: John has got a bit of an obsession with chocolate soya milk at the moment which comes in tetrapak containers – that would be a nice size for square bar soaps and be easier to cut out…

Anyway, long story slightly shorter, what else can I reuse or recycle to make either interesting shaped soaps or simple practical ones? If you make your own (cold-process) soap, what do you use?

Do you have any upcycled moulds that you can reuse again and again rather than destroying (like would happen with the poster tube or my juice containers)?

Or on the flipside, anything you’ve used that you’d urge other people not to use?

(A few notes for non-soap makers: the soap mix at the point of pouring is about body temperature for “cold-process” soaps so plastic melting is not usually an issue, but it is incredibly caustic at this point, and will react to metals other than stainless steel. It’s poured into the mould when it’s hit “trace”, a gloopy rather than full liquid stage, and left to set in the moulds for a few days, then popped out of the moulds to continue “curing” for a few weeks before use.)

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26 Responses to “What can I reuse or recycle to make soap moulds?”

  1. Alexis says:

    I’ve seen a demo on youtube where the guy used a pringles tube – similar to poster tube.

    I’ve used an aluminium baking/roasting tray. What about a plastic garden pot? Afterall the growing season is over, so rather than sticking them in the shed unloved for the winter why not line one or two with baking paper and voila!

    You could also use scrap wood to make a wood mould (these are sold at soap making shops for £50+ so why not make one?

    What about egg cartons? The paper could then be recycled when you’re finished and you’d certainly have some fun shaped soaps. Just rght for bundling different scents together and giving as gifts.

    Remember those boxes people used to store cassette tapes in? I’ve also seen similar for CDs. You may have one or two of those lying around from before iPod etc. That could work.

    Similarly an unused lined foolscap box would work.

  2. Su says:

    I made soap for the first time ever the other day and I used a small non-stick roasting tin, some silicone cup cake moulds and since I was using the thermometer from an old yogurt maker I decided to use the yogurt container too. Since the soap is still in the moulds I can’t comment on how effective they are, though I suspect the it’s going to be very difficult to get the soap out of the yogurt container, as it’s straight sided. I’m also not convinced about this soap, but we’ll see.
    What about chocolate box trays for small, interestingly shaped soap? Or margarine or soft cheese containers?

  3. Petra says:

    My favourite moulds are platic butter pots (more or less rectangles here in Holland), so you can easily make nice slices. And loosing the soap from the mould is also no problem. However the shapes are not very attractive, just practical.
    I also found a heart-shaped plastic box from my girls and used that one as a mould. And I’ve used nicely shaped ice tube boxes from IKEA. But they only give very small guest soaps.

    About the tracing: Did you use a stick mixer? That makes a huge difference. For my first batch I used a normal electric mixer, but tracing took indeed hours. For the next batch, I used a stick mixer and tracing took SECONDS! I was almost too late to pour it into the moulds.

    • Karen says:

      Hi, I’m from holland too, I would like to make soap, but can you get all the ingridients in Holland? And what are the dutch names?

      • Petra says:

        You can find all information (in Dutch :-) ) on http://zeep.vanderleden.com/zeepmaken.php. I started with the simplest recipe on this website with olive oil (olijfolie), lye (natriumhydroxide = caustic soda = gootsteenontstopper), and water. That’s all. So you don’t need to buy any weird ingredients.

  4. ariestess says:

    I do M&P soaps, rather than CP, but I use a LOT of silicon baking molds for my soaps, both small and large. The loaf pans are great for making larger bar soaps. And the silicon makes it absolutely easy to remove the finished soaps.

  5. anna says:

    If you have any silicone ice or baking trays in neat sizes and shapes that aren’t used for anything else, like any leftover heart shapes from Valentine’s, those would work great.

  6. Oraxia says:

    I’ve never made my own soap, and maybe this wouldn’t work, but could you pour it into (lined or unlined) muffin pans? I have both metal and silicone ones and I bet you could use the silicone just as is, and maybe could line a metal pan with cupcake liners?

    Tofu tubs might work for slicing, if you eat tofu, although the shape is nothing special. If you have a high-sided baking sheet, maybe you can make a “sheet” of soap and cut out fun shapes later with a cookie cutter? Can you use cups and slice circles out of those?

  7. Caroline says:

    Would plastic flower pots work for you (maybe with a little something at the bottom to block the holes) – around here there are often people with tons to spare just leaving them out to take…

  8. Medeea says:

    Pringles tubes were the first that came to my mind.
    Then any tetrapack.
    Because I prefer round shaped soaps, why not plastic cosmetic containers (from creams, body lotions). In fact, any plastic container with cylinder shape: shower gel, shampoo etc, yogurt (the small ones)

  9. Medeea says:

    Milk or water plastic bottles. There is an abundance of these everywhere.

  10. Trish says:

    I make home made soap often. besides the silicone you can buy, a great frugal mold is looking out in the large metal containers supermarkets use to throw packaging away in when packing their shelves. often there are hard plactic display molds that yogurt is shipped in, nice for round soaps and the correct hight and diameter. sometimes those ridged plastic displays that things stacked up in, makes a nice ribbed edge to bars.
    easy to pop the soap out of, and if you destroy one, who cares cos you got it free.

    punnets your chicken pieces come in are also for bar batches.
    soap can be left in the mold for ages to dry, as they are almost self stacking as well, and will then definately pop out easy

    Experiment, and you will find some cool shapes that work or dont.

    and dont throw out your last bit of soap – keep the bits and rebatch them to make a bar again when you have enough.

  11. Su says:

    I thought the other day that next time I make soap, I will use empty, rinsed out tins for moulds. Once the soap is hard enough, the bottom could be put off, and used to push the soap out, which could then just be sliced. The tin could go in the recycling as usual.

    • louisa says:

      I’d thought about cans but couldn’t work out how to get the soap out afterwards – scoop it out? slice the side of the can open to cut it out? – so discounted the whole idea. Open the other end & push out – heh, I feel rather silly for missing that ;)

  12. Miss Crafty says:

    Some suggestions:

    1. Cottage cheese containers- will make pretty big soaps but nice round ones, maybe you could use yogurt containers instead

    2. Aluminum cans- I know you said most metal doesn’t work, just mentioning this in case it will happen to work

    3. Tuna cans- do not know what type of metal these are made out of

    4. Old plastic folders- if you happen to have a few of these lying around, you could try rolling it up and taping it, then you could seal up the end with bits from other folders, pocket dividers, used plastic wrap, bits of milk or juice cartons, or the like.

    5. Toilet paper rolls- I know these are not reusable but people always seem to have hundreds of these lying around and they do not know what to do with them. You could seal up the bottom with bits from folders, pocket dividers, used plastic wrap, bits of milk or juice cartons, or the like. You could even use bits of cardboard to seal it up since it will most likely be ruined anyways so it does not really matter. If you happen to have some of theose stickers that organizations will give you for free that are really big and look like bumper stitckers, you could seal up the end with that. Also, if you have some magnets that those same organizations are constantly giving away and you just end up throwing out anyways, you could tape some of those to the bottom.

    Just a few suggestions to get you started on brainstorming, I am sure you will think of much better ideas.

    • Barb says:

      Nice ideas, but you definitely do not want to use any kind of aluminum container or tools with lye. It’ll get really hot and produce hydrogen gas. This can be very dangerous.

  13. Virginia Smith says:

    I am a soap maker from Sydney, Australia & have used Pringle (potato chip) containers, cardboard waxed milk cartons or UHT milk cartons – all washed & dried thoroughly before use, PVC pipe slit down the long side for ease of removal & thick cardboard taped to the base – use rubber bands to hold the pipe together until soap is set then cut into size required. Also silicon cake moulds (6 per mould) are available at K-Mart/Walmart in the shapes of hearts, stars, bears & are great to use as soup moulds & very easy to remove soap when set. I usually stand them on a thick cardboard base for stability whilst soap is setting.I also have a hinged wooden mould with collapsable sides I made (search pattern on the soap making sites) which makes a long bar then I cut the soap to size required once soap is set. Hope this helps!

    • Christine says:

      Hi Virginia. Saw your comment and tried to find the info on how to make a hinged wooden mould but without success :(( Do you know the link and possibly share? Would be really appreciated. Anyone else reading this, please chime in :))

  14. Doreen says:

    Always wanted to make soap, think I’m going to do it now as it sounds great and not too expensive. I have some silicone mould making stuff left over from another project and Im thinking I might start making some Christmas themed mould to poor the mixture into to give as gifts . Where please would you get caustic soda from???

    • louisa says:

      It’s quite common in places that sell a decent range of cleaning supplies – I got mine from a Wilkinsons but I’ve heard of other people buying it from big supermarkets and even a Boots.

      There are a few soap recipes out there that use only items found in supermarkets – eg, I’ve made a 100% olive oil one which is just the cheapest olive oil you can buy (pomace is fine), caustic soda and water, and I’ve made another which is 100% veg fats (olive oil, veg shortening and veg oil) — I think they’re a great entry point to soap making as you can get the ingredients quickly and easily, and it’s easy to use up any leftover ingredients.

  15. ANDREA says:

    I have read a lot of websites for soap making and I am getting confused with trying to work out what is what in Australia e.g what is shortening. Someone told me that cocoa oil is Copha? Anyone who makes soap in Australia is welcome to contact me on audie64@gmail.com I have tried to make soap a couple of times with quite a few fails and I am ready to throw in the towel.

  16. Michele says:

    I’ve just recently started making soap and I read an idea the other day that I wil be trying this weekend. Try PVC pipe pieces for the mold. Close one end up with heavy duty wax paper and rubber bands. Put the soap in with a ladle up to about two inches from the top. Secure the open end and wrap with towels. The soap can be gently pushed out of the pipe for cutting. The article said a little petroleum jelly could be rubbed on the inside of the pipe to make it easier to get soap out. PVC pipe is cheap and comes in all different sizes. It could be used over and over too. I am assuming shorter length pieces would be more convenient for getting soap out easier. Good luck.

  17. Ruana says:

    I am fairly new to soap making and I intend on making melt and pour soap for starters, my questions is, will I be able to re use my silicone pan for baking after I’m done using it for soap. Is there any health hazard in reusing the silicone moulds for baking after making soap in them?. Thank you guys

  18. Jeri says:

    Question, Has anyone ever tried paper coffee cups for molds? They seem to be waxy inside so i think it may work?



  19. Marie says:

    Wilkinson’s and boots no longer sell caustic soda, in fact it’s getting harder and harder to find, I live in Bolton and I have been to every super market, pound shops, discount savers, home bargains, you name it and I’ve probably already been there only to find most big stores boots etc no one is selling caustic soda anymore, the only place I can buy this from is B&Q at almost £5 a drum

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