◆ Soap

Brainwash brain soap mold

A brain-shaped soap bar for a proper brainwash: 90 mm, folds and all, as a silicone mold from printed parts.

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3D render of the brain soap master fused on its printed charcoal base, between the orange and blue walls, with the charcoal clamps behind
Soap ~171 g

A soap bar 90 x 77 mm and about 26 mm high shaped like a brain seen from above: one domed oval split into two hemispheres by a narrow fissure, with the folds running all over the top.

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Made with the box mode of our silicone mold maker in its contoured shape: print the base with the soap master fused onto it face up, the two walls and the clamps, pour about 477 ml of silicone, and the block you get casts the bar face down, so the brain comes out on the show face and the back stays flat.

The gag writes itself: a bar of brainwash for the teacher, the scientist or the friend who needs one after a long week. Pour it in pink with a mint or rosemary scent. The zip carries every printed part, the soap master as its own STL, the tool's own print-settings sheet and a recipe file for the generator.

Shown as a 3D render of the printed mold parts pulled apart around the master, not a photo.

Brainwash brain soap mold at a glance: every printed part with its size, print time, filament, print settings and the three steps to use it

What you need

3
  • About 516 ml of silicone (mix it in one batch)
  • Melt-and-pour soap base, about 94 ml per bar
  • Pink soap colour, a fragrance and rubbing alcohol in a spray bottle

How to cast it

6

  1. Print the base with the master fused onto it, the two walls and the two clamps.

  2. Stand the base on the table. Set each wall down a few centimetres out from it and slide it in over the table until the ridge round the base sits in the groove at its foot, then slide the clamps down over the seams. Once they are on, the walls cannot lift, and the ridge seals the bottom.

  3. Mix 516 ml of silicone in one batch and pour it into a corner, letting it rise around the master until it covers the top.

  4. Once it has cured, take the clamps off, slide the walls straight out and pull the silicone block off the master. That block is your mold.

  5. Turn the block over. Pour melt-and-pour soap at 55 to 60 C, spray the surface with alcohol to pop the bubbles, and let it set for a few hours.

  6. Flex the silicone and push the brain out from the back. Wrap it once it is at room temperature.

Print details

5 h 10 minPrint time
~171 gFilament
5Printed parts
106 × 92 × 62 mmSize (W x D x H)
All print details
Print details
Cast materialSoap
Printed parts5
Size (W x D x H)106 x 92 x 62 mm
Print bed needed129 x 93 mm, 62 mm tall
Filament~171 g
Layer height0.2 mm
Infill15%
SupportsNot needed
DownloadZIP: 5 printed parts (STL) + soap bar master (STL) + print sheet + recipe
Added2026-09-25
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Made with the free Silicone mold maker generator. Upload your own model and get the same kind of mold built around it, in your browser.

Download free on Thingiverse

Free download. Opens the Thingiverse listing in a new tab.

Free for personal use. Selling the pieces you cast needs a commercial licence (Pro or Founder); passing on the file itself is not permitted on any plan. Full terms.

New to casting? Read the silicone mold maker guide.

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Questions about this design

Do the folds of the brain soap fill without air bubbles?

Yes, if you pour slowly into one spot and let the soap flow across the folds. Spray the empty cavity with rubbing alcohol first: it helps the soap run into the narrow grooves, and another spray once it is full pops what is left.

Which colour and scent suit a brainwash soap?

A soft pink reads as a brain straight away. Mint, rosemary or eucalyptus fit the joke (a fresh, clear head). Keep the colour light so the folds throw a shadow and stay visible.

Can I sell the brainwash soaps I make with this mold?

Selling the soaps you cast needs an active commercial licence, which comes with Pro or Founder. Passing on the mold file itself is not permitted on any plan. The licences page has the full terms.

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