Soap Carving for Casting

About: I run Neal's CNC in Hayward, CA, an expert CNC cutting and fabrication service. Check out what we do at I'm a founding member of Noisebridge, a hackerspace in San Francisco, and Ac...

How to carve a bar of soap into a smaller soap shape. Discussion of various tools that can be used for this purpose. A little silliness - the carving I made is a kind of slug thing - I'm going to cast it in plastic and glue one googly eye to the upturning end. See the flat part?

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Step 1: Outline the Basic Shape

Draw a side elevation of the shape you'll carve on the side of the soap. Starting with 2-D on one side of the block is a good way to start thinking in 3-D.

Step 2: Carve Out the Basic Shape

I started doing this carving with a Dremel tool, but quickly found that a knife worked much better for the coarse work. Ivory soap at least is quite soft and carves easily. I tried a cutting blade and a grinding disk. The grinding disk is more effective than the cutting blade but both are slower than knife.

Step 3: Do the Fine Carving

For smoothing out the edges, the Dremel works better than a knife, especially a serrated one. Try several different grinding bits depending on the shape you're working with.

Step 4: It's Soap, Wash It.

For a final smoothing, soap as a medium has this great advantage that it dissolves in water. I didn't want to put it under the tap at first, but really, soap doesn't go away all at once. You do have to rub at it. A wet finger isn't enough - dunk that baby.

I could have gotten this smoother if I'd put more effort into it, but I decided it was Fine. SO my slug will be a bit lumpy... that's OK.

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    13 Discussions


    12 years ago

    I love this idea. Please please add your casting instructable - I'm dying to know how you do it!

    5 replies

    Reply 12 years ago

    I keep saying this... i really will write the casting one, I just need time! Poke me about it again if you think of it.


    Reply 12 years ago on Introduction

    Ha! excellent idea. I'm going to add it to my Not Sleeping list now.

    (for those of you who are Confused, see here)


    13 years ago

    horray 4 dremels!!!


    13 years ago

    I would think that the heat of melted plastic would melt the soap. Is this a different kind of soap or am I wrong?

    1 reply

    Reply 13 years ago

    Sorry I just noticed this question! The plastic isn't melted, actually. It's made like epoxy, from two liquid components, which react chemically to create the finished plastic. There is heat involved in the reaction, but not more than (I'm guessing) about 100F. This will be clearer when I do the casting Instructable, I'm hoping to get to that this weekend as I've done enough work with this now that I am starting to get castings that actually look like the model!


    13 years ago

    Please don't forget to do an instructable on the casting!

    2 replies