The 15-Minute Soap Mold

This article was originally published in the March/April 2013 issue of Saponifier Magazine. I was so taken by the ingenuity of the tutorial that I asked Saponifier if I could reprint it here on Soap Queen. Enjoy! -Anne-Marie P.S. Election sign season is just a few months away!

Personal Touch: The 15-Minute Soap Mold

by Victoria Donaldson

I was never so glad to see anything end, as I was the 2011 elections. Is it just me, or did it go on forever? While driving, I was inundated with political signs for everything from president to dog catcher. After November 6, I decided it was time for the remaining ones to go, so I started plucking them up. They were destined for my local recycling center, only my trip out there ended in the discovery that my recycling center did not handle them. So I decided they would reside in my utility room until I had the time to discover where to ship them.

Then my neighbor asked for help making yard sale signs. A quick cover of spray paint and some lettering and he was set. A last minute, oddly sized, Christmas gift resulted in a mad hunt for a suitable box, bag—anything! After an unsuccessful search led to the utility room, I was desperate. I thought perhaps I could do something with a piece of corrugated plastic. Voila! It was so easy, who needs a recycling center? Then I had a lightbulb moment: if I could make a box, I could make a mold for soap. After a little experimentation, I discovered that creating several in different sizes wasn’t a problem since it’s free, it folds flat for easy storage, and it’s really, really easy. What more could you ask for? Plus it gives you a little feeling of revenge for all the TV plugs you had to sit through.

Supplies Needed:

1 corrugated plastic sign

yard stick or long ruler

metal straight edge

exacto or box knife

wide packaging tape

One: First of all, find a large, flat surface that you don’t care if you cut up. The sign I used was a standard 24 inches by 18 inches. For this tutorial we’ll make a mold for 18 bars of soap 3 inches by 2 inches by 1 inch. So I want the interior of my mold to be 18 inches long, 3 inches wide, and 2 inches deep (plus 1 inch of space to avoid overflowing). The dimensions of your mold are limited only by the size of the sign.

Two: From the top left hand corner, measure down 3 inches and mark. Measure 3 inches further and mark, then another 3 inches and mark. From the top right hand corner, measure and make the same marks down as you did on the left hand side. I used a magic marker for visibility in the photos, but a pencil line will give you a more accurate cut.

Three: Draw a line connecting the right and left hand 9 inch marks and using a metal straightedge, cut along the line with your knife, all the way through. You now have a 9 inch x 24 inch piece. Save the leftover piece for another mold or some other use.

Four: Starting from the top left hand corner, measure 3 inches to the right and mark. Measure 18 inches further and mark. Repeat these measurements and marks starting from the bottom left hand corner.

Five: Draw straight lines connecting your marks. Using light pressure, cut along the lines only part way through the board. Try bending the board along the cuts–if any portion won’t bend, very gently run the knife down those little ribs inside. When all cuts bend, on to the next step.

Step 1

Step 2

Step 3

Six: Pressing down hard, cut out all four corner pieces and discard. Flip over and bend all four sides up.

Step 4

Seven: Tape together end pieces to sides and your mold is done. Note that scotch tape will not hold well. The wide clear tape used on tape guns is ideal. This is especially easy to line with parchment paper since the bottom is exactly the same size as the inside. Turn the mold upside down, lay your paper on the bottom and crease along the edge. Fold as you usually do, insert in mold, make a mark how wide you want your soap bars to be and pour!

Step 5

Step 6

NOTE: Since  corrugated plastic is slightly flexible there may be some bowing in the middle of the long side. You can solve this by pushing the mold up against the wall and resting a heavy bookend/brick/etc. on the other side

In searching for a recycling center, I discovered that wildlife rehabilitation centers, pet shelters, and other worthwhile organizations can use corrugated plastic (also known by brand names such as Coroplast and Correx) and welcome your donations! Also, removing political signs can be unlawful in some areas, even after an election is long over, so check with the local ordinances before you reach for your first sign.

“The 15-Minute Soap Mold”, written by Victoria Donaldson, was published in the March/April 2013 issue of Saponifier Magazine. It is reprinted here with full permission of the publisher,

Retired from the graphic arts industry, Victoria does the layout for Saponifier magazine and dabbles in soap and candle making. A lifetime Florida resident, she spends much of her time with her two grandchildren nearby and visits the youngest in California whenever she can. 

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    • Kelsey says


      We went ahead and removed the coupon code. Sorry for any inconvenience!

      -Kelsey with Bramble Berry

  1. Rose says

    I would like to make a couple of molds. My question is how do I determine what LxW I would use for let says a 3 lb log? What calculations would I be working with? Would I use the amount of total oils? Just asking question because I see lots have how to make but how to determine size for the lb of soap is what I was hope to get. Have a great day

  2. says

    I have tried to “buy” the free issue of Saponifier without success. Etsy rejected the coupon code. Where do I go for it? Love the mold idea!

  3. Kayla says

    When I decided I wanted to try and make soap this was the first mold I used. I found how to make this from youtube actually. If you need a liner for your mold this actually works really well. If you build your own mold build it around this mold. Then all you do is slip it in and take it out when your done.

    • says

      Hi Kayla!

      It really is such a simple and easy way to make a mold, and I’m definitely going to have to look into it when campaign season rolls around again. Thanks for letting us know how well it worked for you! =)

      -Becky with Bramble Berry

  4. Chris says

    Thanks for sharing. So many uses for corrugated plastic. I get mine from a local gas station/convenience store that regularly replaces their corrugated plastic advertising signs. They are a nice size and can be cut for just about anything. Not only do they make great molds, they make great display boards at craft fairs etc.

  5. says

    Love this!!! So creative, and FREE! = ) I was thinking, if there are no election signs left over, there will be TAX season signs left over soon!! (i.e., the ones that say “Taxes done here” etc) Usually if you ask businesses, they will just give them to you once season is over! Especially those stores that are only open through tax season…

  6. Connie says

    I love anything that is trash and make it a treasure… I do have one thought. Would it be possible to use the corrugated part for a very unique ripple in your soaps?? I think it would look cool.. However I am a newbie and have only poured six bars as a trial. I have a lot of practicing ahead of me… With this website I am sure I can conquer it. I love the Soap Queen peeps!!


    Chenille Soft Skin

  7. says

    What an easy and creative way to make an inexpensive mold!

    Thank you Brambleberry/SoapQueen for the free gift of Saponifier magazine’s latest issue. I will enjoy browsing the articles.

  8. says

    Hello :)

    Very educational post! Unfortunately I do not have any leftover election signs….
    Its still a genius project!

    I do have question about how to get the magazine… is there a way to enter the code on brambleberry or is it on

    Thanks for any help. :)

  9. Angel says

    Hi, I’ve been a silent reader of your blog this past month, and it’s given me a huge desire to try out soap making for myself. I’ve been itching to try out M&P soap at present, as I live in a studio apartment and trying CP soap would be madness with the lack of open door spaces for handling lye.

    I do have one burning question. If I melt the glycerin bases in a microwave, can I still use the microwave for heating up food? Or is it advisable to use a separate microwave for heating food instead?

    • Timmi says

      You can use the same microwave for both heating food and melting the glycerin soap. Because glycerin soap is simply… soap. So even if it spilled inside the microwave it wouldn’t pose any threat to your food. Great question by the way.

    • says

      Hi Angel,
      I am so excited that you are getting into soaping! It’s so easy, and as you can see, it’s tons of fun. As for your question, it is definitely okay to use your microwave to heat melt & pour and food. No need to have a separate microwave!

      -Kirsten with Bramble Berry

      • Angel says

        Thanks for the suggestion… I’ll have a look. Although I think I’m getting too ambitious and ahead of myself (I don’t even have any soaping equipment!) and I’m thinking of swirls and flower petals and ombre coloured soaps…. ahhhhhh!

        As I understand it, when melting glycerin soap, its recommended to microwave in short bursts of 30 seconds. Do I remove my pyrex jug from the microwave every 30 seconds and stir the contents? Or do I just leave the jug inside and give it a few seconds rest in between bursts?

        • says

          You want to take it out and stir it every 30 seconds. Just leaving it in there untouched can overheat some parts of the soap. And you don’t want to do that, because it can suddenly boil over (this is from personal experience) or just get a little overcooked and make the soap a darker color. Great news is it’s really easy to clean-up if that does happen – just add water! :)

  10. Moira Casadei says

    Always love getting “something from nothing”!!! Unfortunately, my wooden molds are showing some bulge in the middle, just dont’t think the wall and brick trick will work with wood! I’ll have to devise a “clamp” from the wires holding political signs!!!!

  11. says

    Love this idea. A soaper after my own heart. There is one thing you do need to make sure of though, be certain that the ink /printed side is the OUTSIDE of the mould. The ink leeches into the soap. I know this because…..
    Thanks Saponifier. Love the mag.

  12. Timmi says

    Haha, I did this about 3 months ago when I needed a slab mold and it was too cold out for hubby to build me one. It’s not as insulated as my wooden molds so I stuck it on top of a heating pad with a inverted box over it to creat a little oven of sorts. Worked out perfectly!

    Love how she was able to use recycled signs. If you can’t get your hands on one of those though, they do sell sheets of it at Home Depot. That’s where I got mine. Happy soaping everyone!